Multiple-input multiple-output orthogonal frequency division multiplexing communication system and method for signal compensation

ABSTRACT

Embodiments of the present disclosure provide a method for signal compensation, including: receiving, by a receiver via N receiving antennas, a plurality of channel estimation preamble signals sent by M transmitting antennas of a remote transmitter; determining, by the receiver, channel estimation parameters according to the first pilot signals of the M transmitting antennas contained in the plurality of channel estimation preamble signals; receiving, by the receiver, data signals and second pilot signals sent on a first data symbol by the M transmitting antennas; determining, by the receiver, channel phase shift parameters according to signals arrived at the N receiving antennas which come from the second pilot signals; and determining, by the receiver according to the channel estimation parameters and the channel phase shift parameters, signal compensation for the data signals arrived at the N receiving antennas. Accuracy of demodulation for transmitted data to a certain extent is improved.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/941,839, filed Nov. 16, 2015, which is a continuation ofInternational Patent Application No. PCT/CN2013/090338, filed on Dec.24, 2013, which claims priority to Chinese Patent Application No.201310181256.2, filed on May 16, 2013, all of which are herebyincorporated by reference in their entireties.

TECHNICAL FIELD

Embodiments of the present disclosure relate to the field ofcommunications, and more particularly, to a multiple-inputmultiple-output orthogonal frequency division multiplexing communicationsystem and a method for signal compensation.

BACKGROUND

Future broadband wireless communication systems will meet a variety ofintegrated service needs from voice to multimedia under a premise ofhigh stability and high data transmission rate. To implement fasttransmission of integrated service contents on limited spectrumresource, a technology with very high spectrum efficiency is needed.Multiple-input multiple-output (MIMO) technology fully develops spaceresource, and implements multiple inputs and multiple outputs by use ofa plurality of antennas, and channel capacity may be increased by timeswithout a need of adding spectrum resource or antenna transmissionpower. Orthogonal frequency division multiplexing (OFDM) technology isone of multicarrier narrowband transmissions, and subcarriers thereofare mutually orthogonal, and thus may utilize spectrum resourceseffectively. An effective combination of the two (MIMO-OFDM) mayovercome an adverse influence caused by a multipath effect and frequencyselective fading, realize high reliability of signal transmission, andmay further increase system capacity and improve spectrum efficiency.

However, an MIMO-OFDM system is easily to be affected by phase noise andfrequency offset.

SUMMARY

Embodiments of the present disclosure provide a multiple-inputmultiple-output orthogonal frequency division multiplexing communicationsystem and a method for signal compensation, which can improvedemodulation accuracy of transmitted data to a certain extent.

In a first aspect, a method for signal compensation is provided. Themethod includes: receiving, by a receiver via N receiving antennas, aplurality of channel estimation preamble signals sent by M transmittingantennas of a remote transmitter, wherein the plurality of channelestimation preamble signals contain first pilot signals of the Mtransmitting antennas, and M and N are integers larger than 1;determining, by the receiver, channel estimation parameters from the Mtransmitting antennas to the N receiving antennas according to the firstpilot signals of the M transmitting antennas contained in the pluralityof channel estimation preamble signals; receiving, by the receiver viathe N receiving antennas, data signals and second pilot signals sent ona first data symbol by the M transmitting antennas; determining, by thereceiver, channel phase shift parameters from the M transmittingantennas to the N receiving antennas according to signals arrived at theN receiving antennas which come from the second pilot signals sent onthe first data symbol by the M transmitting antennas; and determining,by the receiver according to the channel estimation parameters from theM transmitting antennas to the N receiving antennas and the channelphase shift parameters from the M transmitting antennas to the Nreceiving antennas, signal compensation for the data signals arrived atthe N receiving antennas that are sent on the first data symbol by the Mtransmitting antennas.

In combination with the first aspect, in a first possible implementationmanner, it is specifically implemented as follows: a subcarrier set forsending a first pilot signal of the m^(th) transmitting antenna in the Mtransmitting antennas is equal to a set of subcarriers of the m^(th)transmitting antenna, ∀m={1, . . . , M}.

In combination with the first aspect or the first possibleimplementation manner of the first aspect, in a second possibleimplementation manner, it is specifically implemented as follows: the Nreceiving antennas are coherent, and the M transmitting antennas arecoherent.

In combination with the second possible implementation manner of thefirst aspect, in a third possible implementation manner, thedetermining, by the receiver, channel phase shift parameters from the Mtransmitting antennas to the N receiving antennas according to signalsarrived at the N receiving antennas which come from the second pilotsignals sent on the first data symbol by the M transmitting antennas,includes: determining, by the receiver according to a signal arrived atthe N receiving antennas which comes from a second pilot signal sent onthe first data symbol by the m^(th) transmitting antenna in the Mtransmitting antennas, channel phase shift parameters from the m^(th)transmitting antenna in the M transmitting antennas to the N receivingantennas, wherein ∀m={1, . . . ,M}.

In combination with the third possible implementation manner of thefirst aspect, in a fourth possible implementation manner, thedetermining, by the receiver according to the signal arrived at the Nreceiving antennas which comes from the second pilot signal sent on thefirst data symbol by the m^(th) transmitting antenna in the Mtransmitting antennas, channel phase shift parameters from the m^(th)transmitting antenna in the M transmitting antennas to the N receivingantennas, includes: if there is more than one subcarrier on the firstdata symbol for sending the second pilot signal, determining, by thereceiver according to signals arrived at the N receiving antennas whichcome from the second pilot signals sent on a plurality of subcarriers ofthe first data symbol by the m^(th) transmitting antenna in the Mtransmitting antennas, multiple groups of channel phase shift parametersfrom the m^(th) transmitting antenna in the M transmitting antennas tothe N receiving antennas, and determining average values of the multiplegroups of channel phase shift parameters as the channel phase shiftparameters from the m^(th) transmitting antenna in the M transmittingantennas to the N receiving antennas.

In combination with the third possible implementation manner of thefirst aspect or the fourth possible implementation manner of the firstaspect, in a fifth possible implementation manner, it is specificallyimplemented as follows: the determining, by the receiver according tothe channel estimation parameters from the M transmitting antennas tothe N receiving antennas and the channel phase shift parameters from theM transmitting antennas to the N receiving antennas, the signalcompensation for the data signals arrived at the N receiving antennasthat are sent on the first data symbol by the M transmitting antennas,is expressed by the following formula:

$\begin{bmatrix}{\hat{x}}_{1}^{k} \\\vdots \\{\hat{x}}_{M}^{k}\end{bmatrix} = {{{\begin{bmatrix}e^{{- j}\;{\overset{\sim}{\theta}}_{k_{1},l}} & \ldots & 0 \\\vdots & \vdots & \vdots \\0 & \ldots & e^{{- j}\;{\overset{\sim}{\theta}}_{k_{M},l}}\end{bmatrix}\left\lbrack {\left\lbrack {\hat{H}}^{k} \right\rbrack^{\dagger}\mspace{11mu}{\hat{H}}^{k}} \right\rbrack}^{- 1}\left\lbrack {\hat{H}}^{k} \right\rbrack}^{\dagger}\begin{bmatrix}{y_{1}^{k}(l)} \\\vdots \\{y_{N}^{k}(l)}\end{bmatrix}}$

wherein {circumflex over (x)}_(m) ^(k) represents a data signaltransmitted on the k^(th) subcarrier of the l^(th) data symbol by them^(th) transmitting antenna in the M transmitting antennas, y_(n)^(k)(l) represents arrived at the n^(th) receiving antenna of thereceiver which comes from a data signal transmitted on the k^(th)subcarrier of the 1^(th) data symbol by the M transmitting antennas,∀m={1, . . . ,M }, ∀n={1, . . . ,N},

^(k) represents a channel estimation parameter matrix on the k^(th)subcarrier between the M transmitting antennas and the N receivingantennas, [

^(k)]^(†) represents a conjugate matrix of

^(k),

_(nm) ^(k) in

^(k) represents a channel estimation parameter on the k^(th) subcarrierbetween the m^(th) transmitting antenna of the remote transmitter andthe n^(th) receiving antenna of the receiver,

_(nm) ^(k)=y_(n) ^(k)(t)/s^(k), ∀n={1, . . . ,N}, k∈K, K represents asubcarrier set of the m^(th) transmitting antenna of the remotetransmitter for transmitting the channel estimation preamble signal,s^(k) represents a pilot signal of the k^(th) subcarrier in theplurality of channel estimation preamble signals, y_(n) ^(k)(t)represents a pilot signal arrived at the n^(th) receiving antenna of thereceiver which comes from a pilot signal on the k^(th) subcarrier in thet^(th) channel estimation preamble signal of the remote transmitter,

$\begin{bmatrix}e^{j\;{\hat{\theta}}_{k_{1},l}} \\\vdots \\e^{j\;{\hat{\theta}}_{k_{M},l}}\end{bmatrix}{\quad\;}$represents channel phase shift parameters for signals arrived at the Nreceiving antennas which are sent on the k^(th) subcarrier of the 1^(th)data symbol by the M transmitting antennas, and is expressed by thefollowing formula:

$\begin{bmatrix}e^{j\;{\hat{\theta}}_{k_{1},l}} \\\vdots \\e^{j\;{\hat{\theta}}_{k_{M},l}}\end{bmatrix}{\quad{= {{{\begin{bmatrix}s_{1}^{k} & \ldots & 0 \\\vdots & \vdots & \vdots \\0 & \ldots & s_{M}^{k}\end{bmatrix}\left\lbrack {\left\lbrack {\hat{H}}^{k} \right\rbrack^{\dagger}\mspace{11mu}{\hat{H}}^{k}} \right\rbrack}^{- 1}\left\lbrack {\hat{H}}^{k} \right\rbrack}^{\dagger}\begin{bmatrix}{y_{1}^{k}(l)} \\\vdots \\{y_{N}^{k}(l)}\end{bmatrix}}}}$

wherein s_(m) ^(k) represents a pilot signal transmitted on the k^(th)subcarrier by the m^(th) transmitting antenna of the remote transmitter,y_(n) ^(k)(l) represents a pilot signal arrived at the n^(th) receivingantenna of the receiver which comes from a pilot signal sent on thek^(th) subcarrier of the 1^(th) data symbol by the M transmittingantennas, and

represents a channel phase shift parameter for the signal arrived at theN receiving antennas that is sent on the k^(th) subcarrier of the l^(th)data symbol by the m^(th) transmitting antenna of the remotetransmitter.

In combination with the first aspect or the first possibleimplementation manner of the first aspect, in a sixth possibleimplementation manner, it is specifically implemented as follows: the Nreceiving antennas are incoherent, and/or the M transmitting antennasare incoherent.

In combination with the sixth possible implementation manner of thefirst aspect, in a seventh possible implementation manner, thedetermining, by the receiver, channel phase shift parameters from the Mtransmitting antennas to the N receiving antennas according to signalsarrived at the N receiving antennas which come from the second pilotsignals sent on the first data symbol by the M transmitting antennas,includes:

determining, by the receiver, the channel phase shift parameters fromthe M transmitting antennas to the N receiving antennas according to allof pilot signals arrived at the N receiving antennas that come from thesecond pilot signals sent on the first data symbol by the M transmittingantennas, wherein a quantity of pilot subcarriers where all of the pilotsignals are located is not smaller than M.

In combination with the seventh possible implementation manner of thefirst aspect, in an eighth possible implementation manner, it isspecifically implemented as follows: the determining, by the receiveraccording to the channel estimation parameters from the M transmittingantennas to the N receiving antennas and the channel phase shiftparameters from the M transmitting antennas to the N receiving antennas,the signal compensation for the data signals arrived at the N receivingantennas that are sent on the first data symbol by the M transmittingantennas, is expressed by the following formula:

$\begin{bmatrix}{\hat{x}}_{1}^{k} \\\vdots \\{\hat{x}}_{M}^{k}\end{bmatrix} = {{\left\lbrack {\left\lbrack H_{\xi}^{k} \right\rbrack^{\dagger}\mspace{11mu} H_{\xi}^{k}} \right\rbrack^{- 1}\left\lbrack H_{\xi}^{k} \right\rbrack}^{\dagger}\begin{bmatrix}{y_{1}^{k}(l)} \\\vdots \\{y_{N}^{k}(l)}\end{bmatrix}}$

wherein {circumflex over (x)}_(m) ^(k) represents a data signaltransmitted on the k^(th) subcarrier of the l^(th) data symbol by them^(th) transmitting antenna in the M transmitting antennas, y_(n)^(k)(l) represents arrived at the n^(th) receiving antenna of thereceiver which comes from a data signal transmitted on the k^(th)subcarrier of the 1^(th) data symbol by the M transmitting antennas,∀m={1, . . . ,M}, ∀n={1, . . . ,N}, [

_(ξ) ^(k)]^(†) represents a conjugate matrix of

_(ξ) ^(k),

${H_{\xi}^{k} = \begin{bmatrix}{{\hat{H}}_{11}^{k}e^{j\;\xi_{11}}} & \ldots & {{\hat{H}}_{1\; M}^{k}e^{j\;\xi_{1\; M}}} \\\vdots & \vdots & \vdots \\{{\hat{H}}_{N\; 1}^{k}e^{j\;\xi_{N\; 1}}} & \ldots & {{\hat{H}}_{N\; M}^{k}e^{j\;\xi_{N\; M}}}\end{bmatrix}},$

_(nm) ^(k) in

_(ξ) ^(k) represents a channel estimation parameter on the k^(th)subcarrier between the m^(th) transmitting antenna of the remotetransmitter and the n^(th) receiving antenna of the receiver,

_(nm) ^(k)=y_(n) ^(k)(t)/s^(k), ∀n={1, . . . ,N}, k∈K, K represents asubcarrier set of the m^(th) transmitting antenna of the remotetransmitter for transmitting the channel estimation preamble signal,s^(k) represents a pilot signal of the k^(th) subcarrier in theplurality of channel estimation preamble signals, y_(n) ^(k)(t)represents a pilot signal arrived at the n^(th) receiving antenna of thereceiver which comes from a pilot signal on the k^(th) subcarrier in thet^(th) channel estimation preamble signal of the remote transmitter,

$\begin{bmatrix}e^{j\;\xi_{11}} & \ldots & e^{j\;\xi_{1M}} \\\vdots & \vdots & \vdots \\e^{j\;\xi_{N\; 1}} & \ldots & e^{j\;\xi_{N\; M}}\end{bmatrix}\quad$represents channel phase shift parameters for signals arrived at the Nreceiving antennas that are sent on the 1th data symbol by the Mtransmitting antennas, and is expressed by the following formula:

$\begin{bmatrix}e^{j\;\xi_{11}} & \ldots & e^{j\;\xi_{1M}} \\\vdots & \vdots & \vdots \\e^{j\;\xi_{N\; 1}} & \ldots & e^{j\;\xi_{N\; M}}\end{bmatrix}{{\left. \quad{= {\left\lbrack \begin{matrix}{\overset{\sim}{H}\;}^{p_{1}} \\\vdots \\{\overset{\sim}{H}\;}^{p_{|p|}}\end{matrix} \right\rbrack^{\dagger}\begin{bmatrix}{\overset{\sim}{H}\;}^{p_{1}} \\\vdots \\{\overset{\sim}{H}\;}^{p_{|p|}}\end{bmatrix}}} \right\rbrack^{- 1}\begin{bmatrix}{\overset{\sim}{H}\;}^{p_{1}} \\\vdots \\{\overset{\sim}{H}\;}^{p_{|p|}}\end{bmatrix}}^{\dagger}\begin{bmatrix}{y_{1}^{p_{1}}(l)} \\\vdots \\{y_{N}^{p_{1}}(l)} \\{y_{1}^{p_{2}}(l)} \\\vdots \\{y_{N}^{p_{p}}(l)}\end{bmatrix}}$

wherein y_(n) ^(p)(l) represents a pilot signal arrived at the Nreceiving antennas which comes from a pilot signal transmitted on apilot subcarrier p of the l^(th) data symbol by the M transmittingantennas, p represents any pilot subcarrier in a pilot subcarrier set{p₁, . . . p_(|p|)} of the l^(th) data symbol, and

^(p) is expressed by the following formula:

${\overset{\sim}{H}}^{p_{1}} = \mspace{706mu}\mspace{50mu}{\begin{bmatrix}{{\hat{H}}_{11}^{p}s_{1}^{p}} & \ldots & {{\hat{H}}_{1M}^{p}s_{M}^{p}} & 0 & \ldots & 0 & 0 & \ldots & 0 \\0 & \ldots & 0 & {{\hat{H}}_{21}^{p}s_{1}^{p}} & \ldots & {{\hat{H}}_{2M}^{p}s_{M}^{p}} & \vdots & \ldots & \vdots \\\vdots & \ldots & \vdots & \vdots & \ldots & \vdots & 0 & \ldots & 0 \\0 & \ldots & 0 & 0 & \ldots & 0 & {{\hat{H}}_{N\; 1}^{p}s_{1}^{p}} & \ldots & {{\hat{H}}_{N\; M}^{p}s_{M}^{p}}\end{bmatrix}.}$

In combination with the sixth possible implementation manner of thefirst aspect, in a ninth possible implementation manner, thedetermining, by the receiver, the channel phase shift parameters fromthe M transmitting antennas to the N receiving antennas according to thesignals arrived at the N receiving antennas which come from the secondpilot signals sent on the first data symbol by the M transmittingantennas, includes: determining, by the receiver according to at leastone group of pilot signals arrived at the n^(th) receiving antenna inthe N receiving antennas which come from the second pilot signals senton the first data symbol by the M transmitting antennas, channel phaseshift parameters from the M transmitting antennas to the n^(th)receiving antenna in the N receiving antennas, wherein each group ofpilot signals in the at least one group of pilot signals contains pilotsignals received on J numbers of subcarriers by the N receivingantennas, and a value of J is not smaller than M.

In combination with the ninth possible implementation manner of thefirst aspect, in a tenth possible implementation manner, thedetermining, by the receiver according to at least one group of pilotsignals arrived at the n^(th) receiving antenna in the N receivingantennas which come from the second pilot signals sent on the first datasymbol by the M transmitting antennas, channel phase shift parametersfrom the M transmitting antennas to the n^(th) receiving antenna in theN receiving antennas, includes: determining, by the receiver, multiplegroups of channel phase shift parameters from the M transmittingantennas to the n^(th) receiving antenna in the N receiving antennasaccording to multiple groups of pilot signals arrived at the n^(th)receiving antenna in the N receiving antennas which come from the secondpilot signals sent on the first data symbol by the M transmittingantennas, and determining an average value of channel phase shiftparameters in the multiple groups of channel phase shift parameterscorresponding to a channel phase shift parameter from the m^(th)transmitting antenna in the M transmitting antennas to the n^(th)receiving antenna in the N receiving antennas as a channel phase shiftparameter from the m^(th) transmitting antenna in the M transmittingantennas to the n^(th) receiving antenna in the N receiving antennas.

In combination with the ninth possible implementation manner of thefirst aspect, in an eleventh possible implementation manner, it isspecifically implemented as follows: the determining, by the receiveraccording to the channel estimation parameters from the M transmittingantennas to the N receiving antennas and the channel phase shiftparameters from the M transmitting antennas to the N receiving antennas,signal compensation for the data signals arrived at the N receivingantennas that are sent on the first data symbol by the M transmittingantennas, is expressed by the following formula:

$\begin{bmatrix}{\hat{x}}_{1}^{k} \\\vdots \\{\hat{x}}_{M}^{k}\end{bmatrix} = {{\left\lbrack {\left\lbrack H_{\xi}^{k} \right\rbrack^{\dagger}\mspace{11mu} H_{\xi}^{k}} \right\rbrack^{- 1}\left\lbrack H_{\xi}^{k} \right\rbrack}^{\dagger}\begin{bmatrix}{y_{1}^{k}(l)} \\\vdots \\{y_{N}^{k}(l)}\end{bmatrix}}$

wherein {circumflex over (x)}_(m) ^(k) represents a data signal obtainedby a receiving terminal by demodulation that is transmitted on thek^(th) subcarrier of the l^(th) data symbol by the m^(th) transmittingantenna, y_(n) ^(k)(l) represents a pilot signal arrived at the n^(th)receiving antenna of the receiver which comes from a pilot signal senton the k^(th) subcarrier of the 1^(th) data symbol by the M transmittingantennas, ∀n={1, . . . ,N}, k∈K, [

_(ξ) ^(k)]^(†) represents a conjugate matrix of

_(ξ) ^(k),

${H_{\xi}^{k} = \begin{bmatrix}{{\hat{H}}_{11}^{k}e^{j\;\xi_{11}}} & \ldots & {{\hat{H}}_{1\; M}^{k}e^{j\;\xi_{1\; M}}} \\\vdots & \vdots & \vdots \\{{\hat{H}}_{N\; 1}^{k}e^{j\;\xi_{N\; 1}}} & \ldots & {{\hat{H}}_{N\; M}^{k}e^{j\;\xi_{N\; M}}}\end{bmatrix}},$

_(nm) ^(k) in

_(ξ) ^(k) represents a channel estimation parameter on the k^(th)subcarrier between the m^(th) transmitting antenna of the remotetransmitter and the n^(th) receiving antenna of the receiver,

_(nm) ^(k)=y_(n) ^(k)(t)/s^(k), ∀n={1, . . . ,N}, k∈K, K represents asubcarrier set of the m^(th) transmitting antenna of the remotetransmitter for transmitting the channel estimation preamble signal,s^(k) represents a pilot signal of the k^(th) subcarrier in theplurality of channel estimation preamble signals, y_(n) ^(k)(t)represents a pilot signal arrived at the n^(th) receiving antenna of thereceiver which comes from a pilot signal on the k^(th) subcarrier in thet^(th) channel estimation preamble signal of the remote transmitter,e^(jξ) ^(n) represents a channel phase shift parameter from the Mtransmitting antennas to the n^(th) receiving antenna in the N receivingantennas and is expressed by the following formula:

$e^{{j\;\xi_{n}}\;} = {\left\lbrack {\begin{bmatrix}{{\hat{H}}_{n\; 1}^{J_{1}}s_{1}^{J_{1}}} & \ldots & {{\hat{H}}_{n\; M}^{J_{1}}s_{M}^{J_{1}}} \\\vdots & \ldots & \vdots \\{{\hat{H}}_{n\; 1}^{J_{J}}s_{1}^{J_{J}}} & \ldots & {{\hat{H}}_{n\; M}^{J_{J}}s_{M}^{J_{J}}}\end{bmatrix}^{\dagger}\begin{bmatrix}{{\hat{H}}_{n\; 1}^{J_{1}}s_{1}^{J_{1}}} & \ldots & {{\hat{H}}_{n\; M}^{J_{1}}s_{M}^{J_{1}}} \\\vdots & \ldots & \vdots \\{{\hat{H}}_{n\; 1}^{J_{J}}s_{1}^{J_{J}}} & \ldots & {{\hat{H}}_{n\; M}^{J_{J}}s_{M}^{J_{J}}}\end{bmatrix}} \right\rbrack^{- 1}{\quad{\begin{bmatrix}{{\hat{H}}_{n\; 1}^{J_{1}}s_{1}^{J_{1}}} & \ldots & {{\hat{H}}_{n\; M}^{J_{1}}s_{M}^{J_{1}}} \\\vdots & \ldots & \vdots \\{{\hat{H}}_{n\; 1}^{J_{J}}s_{1}^{J_{J}}} & \ldots & {{\hat{H}}_{n\; M}^{J_{J}}s_{M}^{J_{J}}}\end{bmatrix}^{\dagger}\begin{bmatrix}{y_{n}^{J_{1}}(l)} \\\vdots \\{y_{n}^{J_{J}}(l)}\end{bmatrix}}\;}}$

wherein y_(n) ^(J)(l) represents a pilot signal arrived at the n^(th)receiving antenna in the N receiving antennas which comes from a pilotsignal transmitted on the pilot subcarrier J of the l^(th) data symbolby the M transmitting antennas, J represents any pilot subcarrier in apilot subcarrier set {J₁, . . . J_(|J|)} of the l^(th) data symbol, ands_(m) ^(J) represents a pilot signal transmitted on the pilot subcarrierJ of the l^(th) data symbol by the m^(th) transmitting antenna in the Mtransmitting antennas.

In combination with the first aspect or any possible implementationmanner from the first possible implementation manner of the first aspectto the eleventh possible implementation manner of the first aspect, in atwelfth possible implementation manner, it is specifically implementedas follows: any two adjacent measurement signals of one of the pluralityof channel estimation preamble signals are isolated by at least one voidsubcarrier.

In a second aspect, a method for transmitting a signal is provided. Themethod includes: sending, by a transmitter via M transmitting antennas,a plurality of channel estimation preamble signals to N receivingantennas of a remote receiver, wherein the plurality of channelestimation preamble signals contain first pilot signals of the Mtransmitting antennas, M and N are integers larger than 1, the firstpilot signals in the plurality of channel estimation preamble signalsare used by the remote receiver for determining channel estimationparameters from the M transmitting antennas to the N receiving antennas,and each one of the plurality of channel estimation preamble signals isseparately transmitted by one transmitting antenna in the M transmittingantennas; and sending, by the transmitter via the M transmittingantennas, data signals and second pilot signals on a data symbol,wherein the second pilot signals are used by the remote receiver fordetermining channel phase shift parameters from the M transmittingantennas to the N receiving antennas, and further determining signalcompensation of the data signals according to the channel estimationparameters and the channel phase shift parameters.

In combination with the second aspect, in a first possibleimplementation manner, it is specifically implemented as follows: anytwo adjacent measurement signals of one of the plurality of channelestimation preamble signals are isolated by at least one voidsubcarrier.

In combination with the second aspect or the first possibleimplementation manner of the second aspect, in a second possibleimplementation manner, it is specifically implemented as follows: thereis one or more subcarriers on the data symbol for sending the secondpilot signals.

In combination with the second aspect or the first possibleimplementation manner of the second aspect or the second possibleimplementation manner of the second aspect, in a third possibleimplementation manner, it is specifically implemented as follows: the Mtransmitting antennas of the transmitter are coherent or incoherent.

In a third aspect, a receiver is provided. The receiver includes Nreceiving antennas and a determining unit, wherein the N receivingantennas are configured to receive a plurality of channel estimationpreamble signals sent by M transmitting antennas of a remotetransmitter, wherein the plurality of channel estimation preamblesignals contain first pilot signals of the M transmitting antennas, andM and N are integers larger than 1; the determining unit is configuredto determine channel estimation parameters from the M transmittingantennas to the N receiving antennas according to the first pilotsignals of the M transmitting antennas contained in the plurality ofchannel estimation preamble signals; the N receiving antennas arefurther configured to receive data signals and second pilot signals senton a first data symbol by the M transmitting antennas; the determiningunit is further configured to determine channel phase shift parametersfrom the M transmitting antennas to the N receiving antennas accordingto signals arrived at the N receiving antennas which come from thesecond pilot signals sent on the first data symbol by the M transmittingantennas; and the determining unit is further configured to determineaccording to the channel estimation parameters from the M transmittingantennas to the N receiving antennas and the channel phase shiftparameters from the M transmitting antennas to the N receiving antennas,signal compensation for the data signals arrived at the N receivingantennas that are sent on the first data symbol by the M transmittingantennas.

In combination with the third aspect, in a first possible implementationmanner, it is specifically implemented as follows: a subcarrier set forsending a first pilot signal of the m^(th) transmitting antenna in the Mtransmitting antennas is equal to a set of subcarriers of the m^(th)transmitting antenna, ∀m={1, . . . ,M}.

In combination with the third aspect or the first possibleimplementation manner of the third aspect, in a second possibleimplementation manner, it is specifically implemented as follows: the Nreceiving antennas are coherent, and the M transmitting antennas arecoherent.

In combination with the second possible implementation manner of thethird aspect, in a third possible implementation manner, it isspecifically implemented as follows: in a process of determining thechannel phase shift parameters from the M transmitting antennas to the Nreceiving antennas according to signals arrived at the N receivingantennas which come from the second pilot signals sent on the first datasymbol by the M transmitting antennas, the determining unit isspecifically configured to:

determine first channel phase shift parameters according to a signalarrived at the N receiving antennas which comes from a second pilotsignal sent on the first data symbol by the m^(th) transmitting antennain the M transmitting antennas, wherein the first channel phase shiftparameters are channel phase shift parameters from the m^(th)transmitting antenna in the M transmitting antennas to the N receivingantennas, ∀m={1, . . . ,M}.

In combination with the third possible implementation manner of thethird aspect, in a fourth possible implementation manner, it isspecifically implemented as follows: in a process of determining,according to the signal arrived at the N receiving antennas which comesfrom the second pilot signal sent on the first data symbol by the m^(th)transmitting antenna in the M transmitting antennas, channel phase shiftparameters from the m^(th) transmitting antenna in the M transmittingantennas to the N receiving antennas, the determining unit isspecifically configured to: if there is more than one subcarrier on thefirst data symbol for sending the second pilot signal, determine,according to signals arrived at the N receiving antennas which come fromthe second pilot signals sent on a plurality of subcarriers of the firstdata symbol by the m^(th) transmitting antenna in the M transmittingantennas, multiple groups of channel phase shift parameters from them^(th) transmitting antenna in the M transmitting antennas to the Nreceiving antennas, and determine average values of the multiple groupsof channel phase shift parameters as the channel phase shift parametersfrom the m^(th) transmitting antenna in the M transmitting antennas tothe N receiving antennas.

In combination with the third possible implementation manner of thethird aspect or the fourth possible implementation manner of the thirdaspect, in a fifth possible implementation manner, it is specificallyimplemented as follows: determining, by the determining unit, the signalcompensation for the data signals arrived at the N receiving antennasthat are sent on the first data symbol by the M transmitting antennas,is expressed by the following formula:

$\begin{bmatrix}{\hat{x}}_{1}^{k} \\\vdots \\{\hat{x}}_{M}^{k}\end{bmatrix} = {{{\begin{bmatrix}e^{{- j}{\overset{\sim}{\theta}\;}_{k_{1},l}} & \ldots & 0 \\\vdots & \vdots & \vdots \\0 & \ldots & e^{{- j}\;{\overset{\sim}{\theta}\;}_{k_{M},l}}\end{bmatrix}\left\lbrack {\left\lbrack {\hat{H}}^{k} \right\rbrack^{\dagger}{\hat{H}}^{k}} \right\rbrack}^{- 1}\left\lbrack {\hat{H}}^{k} \right\rbrack}^{\dagger}\begin{bmatrix}{y_{1}^{k}(l)} \\\vdots \\{y_{N}^{k}(l)}\end{bmatrix}}$

wherein {circumflex over (x)}_(m) ^(k) represents a data signaltransmitted on the k^(th) subcarrier of the l^(th) data symbol by them^(th) transmitting antenna in the M transmitting antennas, y_(n)^(k)(l) represents a signal arrived at the n^(th) receiving antenna ofthe receiver which comes from a data signal transmitted on the k^(th)subcarrier of the 1^(th) data symbol by the M transmitting antennas,∀m={1, . . . ,M}, ∀n={1, . . . ,N},

^(k) represents a channel estimation parameter matrix on the k^(th)subcarrier between the M transmitting antennas and the N receivingantennas, [

^(k)]^(†) represents a conjugate matrix of

^(k),

_(nm) ^(k) in

^(k) represents a channel estimation parameter on the k^(th) subcarrierbetween the m^(th) transmitting antenna of the remote transmitter andthe n^(th) receiving antenna of the receiver,

_(nm) ^(k)=y_(n) ^(k)(t)/s^(k), ∀n={1, . . . ,N}, k∈K, K represents asubcarrier set of the m^(th) transmitting antenna of the remotetransmitter for transmitting the channel estimation preamble signal,s^(k) represents a pilot signal of the k^(th) subcarrier in theplurality of channel estimation preamble signals, y_(n) ^(k)(t)represents a pilot signal arrived at the n^(th) receiving antenna of thereceiver which comes from a data signal transmitted on the k^(th)subcarrier of the 1^(th) data symbol by the M transmitting antennas,

$\begin{bmatrix}e^{j\;{\hat{\theta}}_{k_{1},l}} \\\vdots \\e^{j\;{\hat{\theta}}_{k_{M},l}}\end{bmatrix}{\quad\;}$represents channel phase shift parameters for signals arrived at the Nreceiving antennas which are sent on the k^(th) subcarrier of the 1^(th)data symbol by the M transmitting antennas, and is expressed by thefollowing formula:

$\begin{bmatrix}e^{j\;{\hat{\theta}}_{k_{1},l}} \\\vdots \\e^{j\;{\hat{\theta}}_{k_{M},l}}\end{bmatrix} = {{{\begin{bmatrix}s_{1}^{k} & \ldots & 0 \\\vdots & \vdots & \vdots \\0 & \ldots & s_{M}^{k}\end{bmatrix}\left\lbrack {\left\lbrack {\hat{H}}^{k} \right\rbrack^{\dagger}{\hat{H}}^{k}} \right\rbrack}^{- 1}\left\lbrack {\hat{H}}^{k} \right\rbrack}^{\dagger}\begin{bmatrix}{y_{1}^{k}(l)} \\\vdots \\{y_{N}^{k}(l)}\end{bmatrix}}$

wherein s_(m) ^(k) represents a pilot signal transmitted on the k^(th)subcarrier by the m^(th) transmitting antenna of the remote transmitter,y_(n) ^(k)(l) represents a pilot signal arrived at the n^(th) receivingantenna of the receiver which comes from a pilot signal sent on thek^(th) subcarrier of the data 1^(th) symbol by the M transmittingantennas, and

represents a channel phase shift parameter for the signal arrived at theN receiving antennas that is sent on the k^(th) subcarrier of the l^(th)data symbol by the m^(th) transmitting antenna of the remotetransmitter.

In combination with the third aspect or the first possibleimplementation manner of the third aspect, in a sixth possibleimplementation manner, it is specifically implemented as follows: the Nreceiving antennas are incoherent, and/or the M transmitting antennasare incoherent.

In combination with the sixth possible implementation manner of thethird aspect, in a seventh possible implementation manner, it isspecifically implemented as follows: in a process of determining thechannel phase shift parameters from the M transmitting antennas to the Nreceiving antennas according to signals arrived at the N receivingantennas which come from the second pilot signals sent on the first datasymbol by the M transmitting antennas, the determining unit isspecifically configured to determine the channel phase shift parametersfrom the M transmitting antennas to the N receiving antennas accordingto all of pilot signals arrived at the N receiving antennas which comefrom the second pilot signals sent on the first data symbol by the Mtransmitting antennas, wherein a quantity of pilot subcarriers where allof the pilot signals are located is not smaller than M.

In combination with the seventh possible implementation manner of thethird aspect, in an eighth possible implementation manner, it isspecifically implemented as follows: determining, by the determiningunit, signal compensation for the data signals arrived at the Nreceiving antennas that are sent on the first data symbol by the Mtransmitting antennas, is expressed by the following formula:

$\begin{bmatrix}{\hat{x}}_{1}^{k} \\\vdots \\{\hat{x}}_{M}^{k}\end{bmatrix} = {{\left\lbrack {\left\lbrack H_{\xi}^{k} \right\rbrack^{\dagger}H_{\xi}^{k}} \right\rbrack^{- 1}\left\lbrack H_{\xi}^{k} \right\rbrack}^{\dagger}\begin{bmatrix}{y_{1}^{k}(l)} \\\vdots \\{y_{N}^{k}(l)}\end{bmatrix}}$

wherein {circumflex over (x)}_(m) ^(k) represents a data signaltransmitted on the k^(th) subcarrier of the l^(th) data symbol by them^(th) transmitting antenna in the M transmitting antennas, y_(n)^(k)(l) represents a signal arrived at the n^(th) receiving antenna ofthe receiver which comes from a data signal transmitted on the k^(th)subcarrier of the 1^(th) data symbol by the M transmitting antennas,∀m={1, . . . ,M}, ∀n={1, . . . ,N}, [

_(ξ) ^(k)]^(†) represents a conjugate matrix of

_(ξ) ^(k),

${H_{\xi}^{k} = \begin{bmatrix}{{\hat{H}}_{11}^{k}e^{j\;\xi_{11}}} & \ldots & {{\hat{H}}_{1M}^{k}e^{j\;\xi_{1M}}} \\\vdots & \vdots & \vdots \\{{\hat{H}}_{N\; 1}^{k}e^{j\;\xi_{N\; 1}}} & \ldots & {{\hat{H}}_{N\; M}^{k}e^{j\;\xi_{N\; M}}}\end{bmatrix}},$

_(nm) ^(k) in

_(ξ) ^(k) represents a channel estimation parameter on the k^(th)subcarrier between the m^(th) transmitting antenna of the remotetransmitter and the n^(th) receiving antenna of the receiver,

_(nm) ^(k)=y_(n) ^(k)(t)/s^(k), ∀n={1, . . . ,N}, k∈K, K represents asubcarrier set of the m^(th) transmitting antenna of the remotetransmitter for transmitting the channel estimation preamble signal,s^(k) represents a pilot signal of the k^(th) subcarrier in theplurality of channel estimation preamble signals, y_(n) ^(k)(t)represents a pilot signal arrived at the n^(th) receiving antenna of thereceiver which comes from a pilot signal on the k^(th) subcarrier in thet^(th) channel estimation preamble signal of the remote transmitter,

$\begin{bmatrix}e^{j\;\xi_{11}} & \ldots & e^{j\;\xi_{1M}} \\\vdots & \vdots & \vdots \\e^{j\;\xi_{N\; 1}} & \ldots & e^{j\;\xi_{N\; M}}\end{bmatrix}\quad$represents channel phase shift parameters for signals arrived at the Nreceiving antennas that are sent on the 1^(th) data symbol by the Mtransmitting antennas, and is expressed by the following formula:

${\begin{bmatrix}e^{j\;\xi_{11}} & \ldots & e^{j\;\xi_{1M}} \\\vdots & \vdots & \vdots \\e^{j\;\xi_{N\; 1}} & \ldots & e^{j\;\xi_{N\; M}}\end{bmatrix} = {{{\left\lbrack \begin{matrix}{\overset{\sim}{H}}^{p_{1}} \\\vdots \\{\overset{\sim}{H}}^{p_{|p|}}\end{matrix} \right\rbrack^{\dagger}\begin{bmatrix}{\overset{\sim}{H}}^{p_{1}} \\\vdots \\{\overset{\sim}{H}}^{p_{|p|}}\end{bmatrix}}^{- 1}\left\lbrack \begin{matrix}{\overset{\sim}{H}}^{p_{1}} \\\vdots \\{\overset{\sim}{H}}^{p_{|p|}}\end{matrix} \right\rbrack}^{\dagger}\begin{bmatrix}{y_{1}^{p_{1}}(l)} \\\vdots \\{y_{N}^{p_{1}}(l)} \\{y_{1}^{p_{2}}(l)} \\\vdots \\{y_{N}^{p_{p}}(l)}\end{bmatrix}}}\;$

wherein y_(n) ^(p)(l) represents a pilot signal arrived at the Nreceiving antennas which comes from a pilot signal transmitted on apilot subcarrier p of the l^(th) data symbol by the M transmittingantennas, p represents any pilot subcarrier in a pilot subcarrier set{p₁, . . . p_(|p|)} of the l^(th) data symbol, and

^(p) is expressed by the following formula:

${\begin{bmatrix}{{\hat{H}}_{11}^{p}s_{1}^{p}} & \ldots & {{\hat{H}}_{1M}^{p}s_{M}^{p}} & 0 & \ldots & 0 & 0 & \ldots & 0 \\0 & \ldots & 0 & {{\hat{H}}_{21}^{p}s_{1}^{p}} & \ldots & {{\hat{H}}_{2M}^{p}s_{M}^{p}} & \vdots & \ldots & \vdots \\\vdots & \ldots & \vdots & \vdots & \vdots & \vdots & 0 & \ldots & 0 \\0 & \ldots & 0 & 0 & \ldots & 0 & {{\hat{H}}_{N1}^{p}s_{1}^{p}} & \ldots & {{\hat{H}}_{N\; M}^{p}s_{M}^{p}}\end{bmatrix}}.$

In combination with the sixth possible implementation manner of thethird aspect, in a ninth possible implementation manner, it isspecifically implemented as follows: in a process of determining thechannel phase shift parameters from the M transmitting antennas to the Nreceiving antennas according to the signals arrived at the N receivingantennas which come from the second pilot signals sent on the first datasymbol by the M transmitting antennas, the determining unit isspecifically configured to determine, according to at least one group ofpilot signals arrived at the n^(th) receiving antenna in the N receivingantennas which come from the second pilot signals sent on the first datasymbol by the M transmitting antennas, channel phase shift parametersfrom the M transmitting antennas to the n^(th) receiving antenna in theN receiving antennas, wherein each group of pilot signals in the atleast one group of pilot signals contains pilot signals received on Jnumbers of subcarriers by the N receiving antennas, and a value of J isnot smaller than M.

In combination with the ninth possible implementation manner of thethird aspect, in a tenth possible implementation manner, it isspecifically implemented as follows: in a process of determining,according to at least one group of pilot signals arrived at the n^(th)receiving antenna in the N receiving antennas which come from the secondpilot signals sent on the first data symbol by the M transmittingantennas, channel phase shift parameters from the M transmittingantennas to the n^(th) receiving antenna in the N receiving antennas,the determining unit is specifically configured to determine multiplegroups of channel phase shift parameters from the M transmittingantennas to the n^(th) receiving antenna in the N receiving antennasaccording to multiple groups of pilot signals arrived at the n^(th)receiving antenna in the N receiving antennas which come from the secondpilot signals sent on the first data symbol by the M transmittingantennas, and determine an average value of corresponding channel phaseshift parameters in the multiple groups of channel phase shiftparameters of a channel phase shift parameter from the m^(th)transmitting antenna in the M transmitting antennas to the n^(th)receiving antenna in the N receiving antennas as a channel phase shiftparameter from the m^(th) transmitting antenna in the M transmittingantennas to the n^(th) receiving antenna in the N receiving antennas.

In combination with the ninth possible implementation manner of thethird aspect, in an eleventh possible implementation manner, it isspecifically implemented as follows: determining, by the determiningunit, signal compensation for the data signals arrived at the Nreceiving antennas that are sent on the first data symbol by the Mtransmitting antennas, is expressed by the following formula:

${\begin{bmatrix}{\hat{x}}_{1}^{k} \\\vdots \\{\hat{x}}_{M}^{k}\end{bmatrix} = {{\left\lbrack {\left\lbrack H_{\xi}^{k} \right\rbrack^{\dagger}{\hat{H}}_{\xi}^{k}} \right\rbrack^{- 1}\left\lbrack H_{\xi}^{k} \right\rbrack}^{\dagger}\begin{bmatrix}{y_{1}^{k}(l)} \\\vdots \\{y_{N}^{k}(l)}\end{bmatrix}}}\;$

wherein, {circumflex over (x)}_(m) ^(k) represents a data signalobtained by a receiving terminal by demodulation that is transmitted onthe k^(th) subcarrier of the l^(th) data symbol by the m^(th)transmitting antenna, y_(n) ^(k)(l) represents a pilot signal arrived atthe nth receiving antenna of the receiver which comes from a pilotsignal sent on the kth subcarrier of the lth data symbol by the Mtransmitting antennas, ∀n={1, . . . ,N}, k∈K, [

_(ξ) ^(k)]^(†) represents a conjugate matrix of

_(ξ) ^(k),

$H_{\xi}^{k} = \begin{bmatrix}{{\hat{H}}_{11}^{k}e^{j\;\xi_{11}}} & \ldots & {{\hat{H}}_{1M}^{k}e^{j\;\xi_{1M}}} \\\vdots & \vdots & \vdots \\{{\hat{H}}_{N\; 1}^{k}e^{j\;\xi_{N\; 1}}} & \ldots & {{\hat{H}}_{N\; M}^{k}e^{j\;\xi_{N\; M}}}\end{bmatrix}$

_(nm) ^(k) in

_(ξ) ^(k) represents a channel estimation parameter on the k^(th)subcarrier between the m^(th) transmitting antenna of the remotetransmitter and the n^(th) receiving antenna of the receiver.

_(nm) ^(k)=y_(n) ^(k)(t)/s^(k), ∀n={1, . . . ,N}, k∈K, K represents asubcarrier set of the m^(th) transmitting antenna of the remotetransmitter for transmitting the channel estimation preamble signal,s^(k) represents a pilot signal of the k^(th) subcarrier in theplurality of channel estimation preamble signals, y_(n) ^(k)(t)represents a pilot signal arrived at the n^(th) receiving antenna of thereceiver which comes from a pilot signal on the k^(th) subcarrier in thet^(th) channel estimation preamble signal of the remote transmitter,e^(jξ) ^(n) represents a channel phase shift parameter matrix from the Mtransmitting antennas to the n^(th) receiving antenna in the N receivingantennas and is expressed by the following formula:

$e^{j\;\xi_{n}} = {{\left\lbrack {\begin{bmatrix}{{\hat{H}}_{n\; 1}^{J_{1}}s_{1}^{J_{1}}} & \ldots & {{\hat{H}}_{n\; M}^{J_{1}}s_{M}^{J_{1}}} \\\vdots & \ldots & \vdots \\{{\hat{H}}_{n\; 1}^{J_{J}}s_{1}^{J_{J}}} & \ldots & {{\hat{H}}_{n\; M}^{J_{J}}s_{M}^{J_{J}}}\end{bmatrix}^{\dagger}\begin{bmatrix}{{\hat{H}}_{n\; 1}^{J_{1}}s_{1}^{J_{1}}} & \ldots & {{\hat{H}}_{n\; M}^{J_{1}}s_{M}^{J_{1}}} \\\vdots & \ldots & \vdots \\{{\hat{H}}_{n\; 1}^{J_{J}}s_{1}^{J_{J}}} & \ldots & {{\hat{H}}_{n\; M}^{J_{J}}s_{M}^{J_{J}}}\end{bmatrix}} \right\rbrack^{- 1}\mspace{70mu}\mspace{355mu}\begin{bmatrix}{{\hat{H}}_{n\; 1}^{J_{1}}s_{1}^{J_{1}}} & \ldots & {{\hat{H}}_{n\; M}^{J_{1}}s_{M}^{J_{1}}} \\\vdots & \ldots & \vdots \\{{\hat{H}}_{n\; 1}^{J_{J}}s_{1}^{J_{J}}} & \ldots & {{\hat{H}}_{n\; M}^{J_{J}}s_{M}^{J_{J}}}\end{bmatrix}}^{\dagger}\begin{bmatrix}{y_{n}^{J_{1}}(l)} \\\vdots \\{y_{n}^{J_{J}}(l)}\end{bmatrix}}$

wherein y_(n) ^(J)(l) represents a pilot signal arrived at the n^(th)receiving antenna in the N receiving antennas which comes from a pilotsignal transmitted on the pilot subcarrier J of the l^(th) data symbolby the M transmitting antennas, J represents any pilot subcarrier in apilot subcarrier set {J₁, . . . J_(|J|)} of the l^(th) data symbol, ands_(m) ^(J) represents a pilot signal transmitted on the pilot subcarrierJ of the l^(th) data symbol by the m^(th) transmitting antenna in the Mtransmitting antennas.

In combination with the third aspect or any possible implementationmanner from the first possible implementation manner of the third aspectto the eleventh possible implementation manner of the third aspect, in atwelfth possible implementation manner, it is specifically implementedas follows: any two adjacent measurement signals of one of the pluralityof channel estimation preamble signals are isolated by at least one voidsubcarrier.

In a fourth aspect, a transmitter is provided. The transmitter includes:a signal generating unit and M transmitting antennas, wherein the signalgenerating unit is configured to generate a plurality of channelestimation preamble signals, wherein the plurality of channel estimationpreamble signals contain first pilot signals of the M transmittingantennas, M and N are integers larger than 1, the first pilot signals inthe plurality of channel estimation preamble signals are used by aremote receiver for determining channel estimation parameters from the Mtransmitting antennas to the N receiving antennas; the M transmittingantennas are configured to send the plurality of channel estimationpreamble signals to N receiving antennas of the remote receiver, whereineach one of the plurality of channel estimation preamble signals isseparately transmitted by one transmitting antenna in the M transmittingantennas; the signal generating unit is further configured to generatedata signals and second pilot signals; the M transmitting antennas arefurther configured to send the data signals and the second pilot signalson a data symbol, wherein the second pilot signals are used by theremote receiver for determining channel phase shift parameters from theM transmitting antennas to the N receiving antennas, and furtherdetermining signal compensation of the data signals according to thechannel estimation parameters and the channel phase shift parameters.

In combination with the fourth aspect, in a first possibleimplementation manner, it is specifically implemented as follows: anytwo adjacent measurement signals of one of the plurality of channelestimation preamble signals are isolated by at least one voidsubcarrier.

In combination with the fourth aspect or the first possibleimplementation manner of the fourth aspect, in a second possibleimplementation manner, it is specifically implemented as follows: thereis one or more subcarriers on the data symbol for sending the secondpilot signals.

In combination with the fourth aspect or the first possibleimplementation manner of the fourth aspect or the second possibleimplementation manner of the second aspect, in a third possibleimplementation manner, it is specifically implemented as follows: the Mtransmitting antennas of the transmitter are coherent or incoherent.

In the fifth aspect, a multiple-input multiple-output orthogonalfrequency division multiplexing communication system is provided. Thesystem includes a receiver and a transmitter, wherein the receiver isthe receiver in the third aspect or in any possible implementationmanner from the first possible implementation manner of the third aspectto the twelfth possible implementation manner of the third aspect in thepresent disclosure, and the transmitter is the transmitter in the fourthaspect or in the first possible implementation manner of the fourthaspect or the second possible implementation manner of the fourth aspectin the present disclosure.

By adopting the multiple-input multiple-output orthogonal frequencydivision multiplexing communication system and the method for signalcompensation provided by the embodiments of the present disclosure, thereceiver determines the signal compensation of the data signalsaccording to the channel estimation parameters from the transmittingantennas of the remote transmitter to the receiving antennas of thereceiver and the channel phase shift parameters of the transmittingantennas of the remote transmitter on the first data symbol, therebyimproving demodulation accuracy of transmitted data to a certain extent.

BRIEF DESCRIPTION OF DRAWINGS

To illustrate the technical solutions in the embodiments of the presentdisclosure or in the prior art more clearly, a brief introduction on theaccompanying drawings which are needed in the description of theembodiments or the prior art is given below. Apparently, theaccompanying drawings in the description below are merely some of theembodiments of the present disclosure, based on which other drawings maybe obtained by those of ordinary skill in the art without any creativeeffort.

FIG. 1 is a flowchart of a method for signal compensation in anembodiment of the present disclosure.

FIG. 2 is a schematic diagram of a transmission manner of a channelpreamble signal in an embodiment of the present disclosure.

FIG. 3 is a schematic diagram of another transmission manner of achannel preamble signal in an embodiment of the present disclosure.

FIG. 4 is a schematic diagram of a pilot of a data symbol in anembodiment of the present disclosure.

FIG. 5 is a schematic diagram of a functionality partition ofsubcarriers in an embodiment of the present disclosure.

FIG. 6 is a flowchart of a method for sending a signal in an embodimentof the present disclosure.

FIG. 7 is a schematic diagram of a structure of a receiver in anembodiment of the present disclosure.

FIG. 8 is a schematic diagram of another structure of a receiver in anembodiment of the present disclosure.

FIG. 9 is a schematic diagram of a structure of an MIMO-OFDM system inan embodiment of the present disclosure.

FIG. 10 is a flowchart of another method for signal compensation in anembodiment of the present disclosure.

FIG. 11 is a schematic diagram of another transmission manner of achannel preamble signal in an embodiment of the present disclosure.

FIG. 12 is a flowchart of another method for sending a signal in anembodiment of the present disclosure.

FIG. 13 is a schematic diagram of another structure of a receiver in anembodiment of the present disclosure.

FIG. 14 is a schematic diagram of a structure of a transmitter in anembodiment of the present disclosure.

FIG. 15 is a schematic diagram of another structure of a receiver in anembodiment of the present disclosure.

FIG. 16 is a schematic diagram of another structure of a transmitter inan embodiment of the present disclosure.

FIG. 17 is a schematic diagram of a structure of an MIMO-OFDM system inan embodiment of the present disclosure.

DESCRIPTION OF EMBODIMENTS

The technical solution in the embodiments of the present disclosure willbe described clearly and fully hereinafter in conjunction with thedrawings in the embodiments of the present disclosure. Apparently, theembodiments described below are merely a part, but not all, of theembodiments of the present disclosure. All of the other embodiments,which are obtained by those of ordinary skill in the art based on theembodiments of the present disclosure without any creative effort, fallinto the protection scope of the present disclosure.

The technical solutions of the present disclosure may be applied tovarious communication systems, such as, for example, a global system ofmobile communication (GSM), a code division multiple access (CDMA)system, wideband code division multiple access (WCDMA), general packetradio service wireless (GPRS), long term evolution (LTE), etc.

A user equipment (UE), which may also be referred to as a mobileterminal, a mobile user equipment and the like, may communicate with oneor multiple core networks through a radio access network (RAN). The userequipment may be a mobile terminal, such as, for example, a mobiletelephone (or referred to as a “cellular” telephone) and a computerhaving a mobile terminal, such as, for example, may be a portable,pocket, hand-held, computer inbuilt or vehicle-mounted mobile apparatus,and they exchange language and/or data with a radio access network.

A base station may be a base transceiver station (BTS) in GSM or CDMA,or may be a base station (NodeB) in WCDMA or an evolutional base station(eNB or e-NodeB, evolutional Node B) in LTE, which is not limited by thepresent disclosure. However, for the convenience of description, eNB istaken as an example for illustration in the following embodiments.

In order to facilitate understanding of embodiments of the presentdisclosure, several elements which will be introduced in thedescriptions of the embodiments of the present disclosure are firstlyillustrated herein.

Receiving antennas of a receiver being coherent refers to that allreceiving antennas of the receiver adopt a same local frequency.

Transmitting antennas of a transmitter being coherent refers to that alltransmitting antennas of the transmitter adopt a same local frequency.

Receiving antennas of a receiver being incoherent refers to that localfrequencies adopted by all receiving antennas of the receiver are notcompletely the same, and there exists at least two receiving antennasadoting different local frequencies.

Transmitting antennas of a transmitter being incoherent refers to thatlocal frequencies adopted by all transmitting antennas of thetransmitter are not completely the same, and there exists at least twotransmitting antennas adoting different local frequencies.

Receiving and sending being incoherent may include the following threeconditions: only the receiving antennas are incoherent, only thetransmitting antennas are incoherent, and both the receiving antennasand the transmitting antennas are incoherent.

FIG. 1 is a flowchart of a method for signal compensation in anembodiment of the present disclosure. The method shown in FIG. 1 isexecuted by a receiver. The receiver mentioned herein refers to areceiving end device of an MIMO-OFDM system, and it may be a basestation, a mobility management entity (MME), a gateway or other networkelement, which is not limited herein in the embodiment of the presentdisclosure.

101, the receiver receives, via N receiving antennas, a plurality ofchannel estimation preamble signals sent by M transmitting antennas of aremote transmitter, wherein the plurality of channel estimation preamblesignals contain measurement signals of the M transmitting antennas ofthe remote transmitter, where M and N are integers larger than 1.

102, the receiver determines channel estimation parameters and channelphase shift parameters from the M transmitting antennas of the remotetransmitter to the N receiving antennas of the receiver according to themeasurement signals of the M transmitting antennas of the remotetransmitter.

103, the receiver determines signal compensation from the M transmittingantennas of the remote transmitter to the N receiving antennas of thereceiver according to the channel estimation parameters and the channelphase shift parameters.

In the embodiment of the present disclosure, the channel estimationparameters and the channel phase shift parameters are determinedaccording to the measurement signals of the remote transmitter, and thesignal compensation is further determined, thereby improving accuracy ofan estimated value of transmitted data.

Optionally, a subcarrier set for sending a measurement signal of them^(th) transmitting antenna in the M transmitting antennas is equal to aset of subcarriers of the m^(th) transmitting antenna, where ∀m={1, . .. ,M}. By sending the measurement signal on an entire range of carriersof one transmitting antenna, a receiver at a receiving end is enabled toobtain the channel estimation parameters and the channel phase shiftparameters of all subcarriers of the transmitting antenna.

In the embodiment of the present disclosure, a measurement signal may bea preset measurement signal. The transmitter and the receiver mayappoint a signal parameter of the measurement signal in advance, suchas, for example, a transmitting power and the like; or, the transmitterand the receiver may determine a signal parameter of the measurementsignal according to protocol regulation.

Preferably, the measurement signal may include a pilot signal. Ofcourse, a possibility of using other signal as the measurement signal isnot excluded.

Optionally, the determining, by the receiver, the channel estimationparameters and the channel phase shift parameters from the Mtransmitting antennas of the remote transmitter to the N receivingantennas of the receiver according to the measurement signals of the Mtransmitting antennas of the remote transmitter, may be specificallyimplemented as follows: the receiver determines the channel estimationparameters from the M transmitting antennas of the remote transmitter tothe N receiving antennas of the receiver according to measurementsignals transmitted by the M transmitting antennas of the remotetransmitter and measurement signals received by the N receiving antennasof the receiver; and the receiver determines the channel phase shiftparameters from the M transmitting antennas of the remote transmitter tothe N receiving antennas of the receiver according to the measurementsignals transmitted by the M transmitting antennas of the remotetransmitter, the measurement signals received by the N receivingantennas of the receiver, and the channel estimation parameters from theM transmitting antennas of the remote transmitter to the N receivingantennas of the receiver.

Optionally, as one embodiment, the determining, by the receiver, thechannel estimation parameters and the channel phase shift parametersfrom the M transmitting antennas of the remote transmitter to the Nreceiving antennas of the receiver according to the measurement signalsof the M transmitting antennas of the remote transmitter may include:determining, by the receiver, at least one channel estimation parameterand at least one channel phase shift parameter for the k^(th) subcarrierof the m^(th) transmitting antenna according to at least one measurementsignal on the k^(th) subcarrier of the m^(th)transmitting antenna; anddetermining, by the receiver, an average value of the at least onechannel estimation parameter for the k^(th) subcarrier of the m^(th)transmitting antenna and an average value of the at least one channelphase shift parameter for the k^(th) subcarrier of the m^(th)transmitting antenna as a channel estimation parameter and a channelphase shift parameter for the k^(th) subcarrier of the m^(th)transmitting antenna, wherein the m^(th) transmitting antenna is one ofthe M transmitting antennas, ∀m={1, . . . ,M}.

In embodiment one of the present disclosure, it is assumed that thetransmitter of the MIMO-OFDM system sends the l^(th) channel estimationpreamble signal via the m^(th) transmitting antenna, wherein a pilotsignal in the channel estimation preamble signal is used as themeasurement signal, and a subcarrier set for sending the pilot signal isK. On the k^(th) subcarrier, where k∈K, signals of the N receivingantennas may be expressed by formula (1).

$\begin{matrix}{\begin{bmatrix}{y_{1}^{k}(l)} \\\vdots \\{y_{N}^{k}(l)}\end{bmatrix} = {{{{\underset{H^{k}}{\underset{︸}{\begin{bmatrix}H_{11}^{k} & \ldots & H_{1M}^{k} \\\vdots & \ldots & \vdots \\H_{N\; 1}^{k} & \ldots & H_{N\; M}^{k}\end{bmatrix}}}\mspace{225mu}\begin{bmatrix}0 \\\vdots \\0 \\s^{k} \\0 \\\vdots \\0\end{bmatrix}}e^{j\;\theta_{l}}} + {ICI}_{l} + z_{l}} = {\begin{bmatrix}{H_{1m}^{k}e^{j\;\theta_{l}}s^{k}} \\\vdots \\{H_{N\; m}^{k}e^{j\;\theta_{l}}s^{k}}\end{bmatrix} = {{ICI}_{l} + z_{l}}}}} & (1)\end{matrix}$

where

$\begin{bmatrix}{y_{1}^{k}(l)} \\\vdots \\{y_{N}^{k}(l)}\end{bmatrix}\quad$represents signals received on the k^(th) subcarrier by the N receivingantennas of the receiver;

$\underset{H^{k}}{\underset{︸}{\begin{bmatrix}H_{11}^{k} & \ldots & H_{1M}^{k} \\\vdots & \ldots & \vdots \\H_{N\; 1}^{k} & \ldots & H_{N\; M}^{k}\end{bmatrix}}}$represents channel parameters from the M transmitting antennas of thetransmitter to the N receiving antennas of the receiver, s^(k)represents a pilot signal of the k^(th) subcarrier, e^(jθ) ^(l)represents a phase shift parameter of the l^(th) subcarrier, ICI_(l)represents inter-carrier interference of the l^(th) channel estimationpreamble signal, and z_(l) represents a noise of the l^(th) channelestimation preamble signal.

Formula (2) may be obtained according to LS estimation.

$\begin{matrix}{{{\hat{H}}_{nm}^{k} = {\frac{y_{n}^{k}(l)}{s^{k}} \approx {H_{nm}^{k}e^{j\;\theta_{l}}}}},{{\forall n} = \left\{ {1,\ldots,N} \right\}},{k \in K}} & (2)\end{matrix}$

In order to represent all of channel estimations of the k^(th)subcarrier, namely {

_(nm) ^(k), ∀n,m}, it is assumed that the m^(th) antenna sends in k_(m)numbers of channel estimation preamble signals and the k^(th) subcarrieris a subcarrier for sending a pilot signal, then a channel estimation ofthe k^(th) subcarrier may be expressed by formula (3),

$\begin{matrix}{{{\hat{H}}_{n\; m}^{k} \approx {H_{n\; m}^{k}e^{j\;\theta_{k_{m}}}}},{{\forall n} = \left\{ {1,\cdots,N} \right\}},{{\forall m} = \left\{ {1,\cdots,M} \right\}}} & (3)\end{matrix}$

At a data demodulation stage, it is necessary to track a phase shiftcaused by a phase noise and a frequency offset. Optionally, a pilotsignal may be inserted into an OFDM data symbol, and the phase shift isestimated via the pilot signal. Receiving signals on the k^(th) pilotsubcarrier of the l^(th) OFDM data symbol may be expressed by formula(4).

$\begin{matrix}{\begin{bmatrix}{y_{1}^{k}(l)} \\\vdots \\{y_{N}^{k}(l)}\end{bmatrix} = {{{H^{k}\begin{bmatrix}s_{1}^{k} \\\vdots \\s_{m}^{k}\end{bmatrix}}e^{j\;\theta_{l}}} + {ICI}_{l} + z_{l}}} & (4)\end{matrix}$

Formula (5) may be obtained by substituting formula (3) into formula(4).

$\begin{matrix}{\begin{bmatrix}{y_{1}^{k}(l)} \\\vdots \\{y_{N}^{k}(l)}\end{bmatrix} \approx {{{{\hat{H}}^{k}\begin{bmatrix}s_{1}^{k} & \ldots & 0 \\\vdots & \vdots & \vdots \\0 & \ldots & s_{M}^{k}\end{bmatrix}}\begin{bmatrix}e^{j\;\theta_{k_{\;^{1,l}}}} \\\vdots \\e^{j\;\theta_{k_{M^{,l}}}}\end{bmatrix}} + {ICI}_{l} + z_{l}}} & (5)\end{matrix}$

Formula (6) may be obtained by the LS estimation.

$\begin{matrix}{\begin{bmatrix}e^{j\;{\hat{\theta}}_{k_{\;^{1^{,l}}}}} \\\vdots \\e^{j\;{\hat{\theta}}_{k_{M^{,l}}}}\end{bmatrix} \approx {{{\begin{bmatrix}s_{1}^{k} & \ldots & 0 \\\vdots & \vdots & \vdots \\0 & \ldots & s_{M}^{k}\end{bmatrix}\left\lbrack {\left\lbrack {\hat{H}}^{k} \right\rbrack^{\dagger}{\hat{H}}^{k}} \right\rbrack}^{- 1}\left\lbrack {\hat{H}}^{k} \right\rbrack}^{\dagger}\begin{bmatrix}{y_{1}^{k}(l)} \\\vdots \\{y_{N}^{k}(l)}\end{bmatrix}}} & (6)\end{matrix}$

where θ_(km,l)=θ_(l)−θ_(km), and [

^(k)]^(†) represents a conjugate matrix of

^(k).

If there exists other pilot subcarrier g satisfying k_(m)=g_(m), ∀m,that is, each transmitting antenna simultaneously sends pilot signals onthe subcarriers k and g, and a more accurate estimation may be obtainedby averaging over estimated values obtained from the subcarriers k andg. If there are a plurality of such subcarriers, a more accurateestimated value may be obtained by averaging over the plurality of suchsubcarriers. Specifically, it is assumed that in a set P, if k, g∈P,then k_(m)=g_(m), ∀m, and an average value may be figured out as shownin formula (7).

$\begin{matrix}{{e^{{j\mspace{11mu}{\overset{\sim}{\theta\;}}_{k_{m},l}}\;} = \frac{\sum\limits_{n \in P}e^{j{\hat{\theta}}_{\;_{\;^{{n\; m},l}}}}}{P}},{{\forall m} = \left\{ {1,\ldots,M} \right\}}} & (7)\end{matrix}$

where |P| represents a cardinal number of the set P.

After tracking the phase shift caused by the phase noise and thefrequency offset, it is necessary to compensate data. Specifically,received signals on the d^(th) data subcarrier of the l^(th) OFDM datasymbol may be expressed by formula (8).

$\begin{matrix}{\begin{bmatrix}{y_{1}^{d}(l)} \\\vdots \\{y_{N}^{d}(l)}\end{bmatrix} = {{{H^{d}\begin{bmatrix}x_{1}^{d} \\\vdots \\x_{M}^{d}\end{bmatrix}}e^{j\;\theta_{l}}} + {ICI}_{l} + z_{l}}} & (8)\end{matrix}$

where x_(m) ^(k) represents a QAM signal of the k^(th) subcarriertransmitted by the m^(th) transmitting antenna. Formula (9) may beobtained by substituting formula (3) into formula (8).

$\begin{matrix}{\begin{bmatrix}{y_{1}^{d}(l)} \\\vdots \\{y_{N}^{d}(l)}\end{bmatrix} \approx {{{{\hat{H}}^{d}\begin{bmatrix}x_{1}^{d} & \ldots & 0 \\\vdots & \vdots & \vdots \\0 & \ldots & x_{M}^{d}\end{bmatrix}}\begin{bmatrix}e^{j\;\theta_{d_{\;^{1,l}}}} \\\vdots \\e^{j\;\theta_{d_{\;^{M^{,l}}}}}\end{bmatrix}} + {ICI}_{l} + z_{l}}} & (9)\end{matrix}$

Formula (10) may be obtained by substituting formula (7) into formula(9) and by utilizing the LS estimation method.

$\begin{matrix}{\begin{bmatrix}{\hat{x}}_{1}^{d} \\\vdots \\{\hat{x}}_{M}^{d}\end{bmatrix} \approx {{{\begin{bmatrix}e^{{{- j}\mspace{11mu}{\overset{\sim}{\theta\;}}_{d_{1},1}}\;} & \ldots & 0 \\\vdots & \vdots & \vdots \\0 & \ldots & e^{{{- j}\mspace{11mu}{\overset{\sim}{\theta\;}}_{d_{M},1}}\;}\end{bmatrix}\left\lbrack {\left\lbrack {\hat{H}}^{d} \right\rbrack^{\dagger}{\hat{H}}^{d}} \right\rbrack}^{- 1}\left\lbrack {\hat{H}}^{d} \right\rbrack}^{\dagger}\begin{bmatrix}{y_{1}^{d}(l)} \\\vdots \\{y_{N}^{d}(l)}\end{bmatrix}}} & (10)\end{matrix}$

Formula (10) is a channel compensation formula determined according tothe channel estimation parameters and the channel phase shiftparameters. It should be noted that, in formula (8) to formula (10), aserial number of a subcarrier is represented by d instead of k, so as todistinguish a serial number of a data subcarrier from a serial number ofa pilot subcarrier. A pilot signal s{circumflex over (0)}k in a pilotsubcarrier is known at a receiving end, while a data signal x{circumflexover (0)}d in a data subcarrier d is unknown at the receiving end and isthe data needing to be demodulated.

It should be noted that, although the symbol “≈” is used in formula(10), in a practical demodulation process, a calculation is performed bytaking the symbol “≈” as the symbol “=”, so as to obtain a demodulatedsignal.

In addition, in order to reduce inter-carrier interference (ICI), whenthe transmitting antennas of the transmitter send the channel estimationpreamble signals, a void subcarrier may be inserted between pilotsignals. In one preferable solution, a same number of void subcarriersmay be inserted between the pilot signals. The larger a quantity of theinserted void subcarriers is, the smaller a value of the ICI is.

In embodiment two of the present disclosure, the method in theembodiment of the present disclosure is further illustrated by taking asystem with 2×2 MIMO-OFDM and K=16 numbers of subcarriers as an example.In this case, M=2, and N=2. FIG. 2 is a schematic diagram of atransmission manner of channel preamble signals in an embodiment of thepresent disclosure. In FIG. 2, a void subcarrier is inserted betweenevery two pilot signals, where s^(k)∈{−1,1}, ∀k∈{0, . . . ,15}.

Channel estimations as shown in formula (11) may be obtained accordingto formula (2).

$\begin{matrix}{{{{\hat{H}}_{n\; 1}^{k} = \frac{y_{n}^{k}(1)}{s^{k}}},{{\forall n} = \left\{ {1,2} \right\}},{{k \in \left\{ {0,{2\mspace{11mu}\ldots},12,14} \right\}};}}{{{\hat{H}}_{n\; 1}^{k} = \frac{y_{n}^{k}(2)}{s^{k}}},{{\forall n} = \left\{ {1,2} \right\}},{{k \in \left\{ {1,3,\ldots,13,15} \right\}};}}{{{\hat{H}}_{n\; 2}^{k} = \frac{y_{n}^{k}(3)}{s^{k}}},{{\forall n} = \left\{ {1,2} \right\}},{{k \in \left\{ {0,{2\;\ldots},,12,14} \right\}};}}{{{\hat{H}}_{n\; 2}^{k} = \frac{y_{n}^{k}(4)}{s^{k}}},{{\forall n} = \left\{ {1,2} \right\}},{{k \in \left\{ {1,3,\ldots,13,15} \right\}};}}} & (11)\end{matrix}$

FIG. 4 is a pilot schematic diagram of a data symbol in an embodiment ofthe present disclosure. In FIG. 4, four pilot signals are inserted intoOFDM data symbols and are located on the 2^(nd), 5^(th), 11^(th) and14^(th) subcarriers.

According to formula (7), since the 2^(nd) and the 14^(th) subcarrierstransmit with the 1^(st) and the 3^(rd) channel estimation pilotsignals, and the 5^(th) and the 11^(th) subcarriers transmit with the2^(nd) and the 4^(th) channel estimation pilot signals, formula (12) maybe obtained.

$\begin{matrix}\begin{matrix}{\left. {e^{{j\mspace{11mu}{\overset{\sim}{\theta\;}}_{1,l}}\;} = {\left( {\sum\limits_{{k = 2},{k = 14}}e^{j\;{\hat{\theta}}_{k_{\;^{1^{,l}}}}}} \right)/2}} \right);{e^{{j\mspace{11mu}{\overset{\sim}{\theta\;}}_{3,l}}\;} = {\left( {\sum\limits_{{k = 2},\;{k = 14}}e^{j_{k_{\;^{2^{,l}}}}^{\hat{\theta}}}} \right)/2}};} \\{{e^{{j\mspace{11mu}{\overset{\sim}{\theta\;}}_{2,l}}\;} = {\left( {\sum\limits_{{k = 5},{k = 11}}e^{j\;{\hat{\theta}}_{k_{\;^{1^{,l}}}}}} \right)/2}};{e^{{j\mspace{11mu}{\overset{\sim}{\theta\;}}_{4,l}}\;} = {\left( {\sum\limits_{{k = 5},\;{k = 11}}e^{j_{k_{\;^{2^{,l}}}}^{\hat{\theta}}}} \right)/2}};}\end{matrix} & (12)\end{matrix}$

Finally, at the data demodulation stage, a signal compensation formulaas shown in formula (13) may be determined according to formula (10).

$\begin{matrix}{\begin{bmatrix}{\hat{x}}_{1}^{d} \\{\hat{x}}_{2}^{d}\end{bmatrix} = {{{\begin{bmatrix}e^{{{- j}\mspace{11mu}{\overset{\sim}{\theta\;}}_{d_{1},l}}\;} & 0 \\0 & e^{{{- j}\mspace{11mu}{\overset{\sim}{\theta\;}}_{d_{2},l}}\;}\end{bmatrix}\left\lbrack {\left\lbrack {\hat{H}}^{d} \right\rbrack^{\dagger}{\hat{H}}^{d}} \right\rbrack}^{- 1}\left\lbrack {\hat{H}}^{d} \right\rbrack}^{\dagger}\begin{bmatrix}{y_{1}^{d}(l)} \\{y_{2}^{d}(l)}\end{bmatrix}}} & (13)\end{matrix}$

where {circumflex over (x)}_(i) ^(d), i=1,2, represents a demodulationsignal on the d^(th) data subcarrier.

In embodiment three of the present disclosure, the method in theembodiment of the present disclosure is further illustrated by taking asystem with 2×2 MIMO-OFDM and K=64 numbers of subcarriers as an example.In this case, M=2, and N=2.

FIG. 5 is a schematic diagram of functional partitioning of subcarriersin an embodiment of the present disclosure. There are only 52 usefulsubcarriers in 64 subcarriers, wherein the 0^(th) to the 5^(th)subcarriers and the 59^(th) to the 63^(rd) subcarriers are voidsubcarriers all the time and do not transmit any information, and the 32^(nd) subcarrier is a direct current subcarrier and does not transmitany information.

A schematic diagram of a transmission manner of a channel preamblesignal in the embodiment of the present disclosure is as shown in FIG.3, in which a void subcarrier is inserted between every two pilotsignals, where s^(k)∈{−1,1}, ∀k∈{6, . . . ,31,33, . . . ,58}.

Channel estimations as shown in formula (14) may be obtained accordingto formula (2).

$\begin{matrix}{{{{\hat{H}}_{n\; 1}^{k} = \frac{y_{n}^{k}(1)}{s^{k}}},{{\forall n} = \left\{ {1,2} \right\}},{{k \in \left\{ {6,8,\ldots,30,34,{\ldots\mspace{14mu} 58}} \right\}};}}{{{\hat{H}}_{n\; 2}^{k} = \frac{y_{n}^{k}(2)}{s^{k}}},{{\forall n} = \left\{ {1,2} \right\}},{{k \in \left\{ {6,8,\ldots,30,34,{\ldots\mspace{11mu} 58}} \right\}};}}{{{\hat{H}}_{n\; 1}^{k} = \frac{y_{n}^{k}(3)}{s^{k}}},{{\forall n} = \left\{ {1,2} \right\}},{{k \in \left\{ {7,9,\ldots,55,57} \right\}};}}{{{\hat{H}}_{n\; 2}^{k} = \frac{y_{n}^{k}(4)}{s^{k}}},{{\forall n} = \left\{ {1,2} \right\}},{{k \in \left\{ {7,9,\ldots,55,57} \right\}};}}} & (14)\end{matrix}$

Eight pilot signals are inserted into OFDM data symbols and arerespectively located on subcarriers P₁={10,22,42,54} and subcarriersP₂={13,25,39,51}.

According to formula (7), since the subcarrier P₁ transmits with the1^(st) and the 2^(nd) channel estimation pilot signals, and thesubcarrier P₂ transmits with the 3^(rd) and the 4^(th) channelestimation pilot signals, formula (15) may be obtained.

$\begin{matrix}\begin{matrix}{{e^{{j\mspace{11mu}{\overset{\sim}{\theta\;}}_{1,l}}\;} = {\left( {\sum\limits_{k \in P_{1}}e^{j\;{\hat{\theta}}_{k_{\;^{1^{,l}}}}}} \right)/2}};{e^{{j\mspace{11mu}{\overset{\sim}{\theta\;}}_{2,l}}\;} = {\left( {\sum\limits_{k \in P_{1}}e^{j_{k_{\;^{2^{,l}}}}^{\hat{\theta}}}} \right)/2}};} \\{{e^{{j\mspace{11mu}{\overset{\sim}{\theta\;}}_{3,l}}\;} = {\left( {\sum\limits_{k \in P_{2}}e^{j\;{\hat{\theta}}_{k_{\;^{1^{,l}}}}}} \right)/2}};{e^{{j\mspace{11mu}{\overset{\sim}{\theta\;}}_{4,l}}\;} = {\left( {\sum\limits_{k \in P_{2}}e^{j_{k_{\;^{2^{,l}}}}^{\hat{\theta}}}} \right)/2}};}\end{matrix} & (15)\end{matrix}$

Formula (16) may be obtained according to formula (6).

$\begin{matrix}{{\begin{bmatrix}e^{j\;{\hat{\theta}}_{k_{1},l}} \\e^{j\;{\hat{\theta}}_{k_{2},l}}\end{bmatrix} \approx {{{\begin{bmatrix}s_{1}^{k} & 0 \\0 & s_{2}^{k}\end{bmatrix}\left\lbrack {\left\lbrack {\hat{H}}^{k} \right\rbrack^{\dagger}{\hat{H}}^{k}} \right\rbrack}^{- 1}\left\lbrack {\hat{H}}^{k} \right\rbrack}^{\dagger}\begin{bmatrix}{y_{1}^{k}(l)} \\{y_{2}^{k}(l)}\end{bmatrix}}},{k \in \left\{ {P_{1},P_{2}} \right\}}} & (16)\end{matrix}$

Finally, at the data demodulation stage, a signal compensation formulaas shown in formula (17) may be determined according to formula (10).

$\begin{matrix}{{\begin{bmatrix}{\hat{x}}_{1}^{d} \\{\hat{x}}_{2}^{d}\end{bmatrix} = {{{\begin{bmatrix}e^{{{- j}\mspace{11mu}{\overset{\sim}{\theta\;}}_{d_{1},l}}\;} & 0 \\0 & e^{{{- j}\mspace{11mu}{\overset{\sim}{\theta\;}}_{d_{2},l}}\;}\end{bmatrix}\left\lbrack {\left\lbrack {\hat{H}}^{d} \right\rbrack^{\dagger}{\hat{H}}^{d}} \right\rbrack}^{- 1}\left\lbrack {\hat{H}}^{d} \right\rbrack}^{\dagger}\begin{bmatrix}{y_{1}^{d}(l)} \\{y_{2}^{d}(l)}\end{bmatrix}}}\;} & (17)\end{matrix}$

where {circumflex over (x)}_(i) ^(d), i=1, 2, represents a demodulationsignal on the d^(th) data subcarrier.

Of course, the method in the embodiment of the present disclosure is notlimited to the method as shown in the above-mentioned embodiment. Nolimitation is set to the number of the transmitting antennas, M, and thenumber of the receiving antennas, N, and meanwhile, and no limitation isset to the number of the subcarriers as well.

In the above-mentioned embodiments one to three, the M transmittingantennas of the transmitter are coherent, and the N receiving antennasof the receiver are also coherent.

FIG. 6 is a flowchart of a method for sending a signal in an embodimentof the present disclosure. The method shown in FIG. 6 is executed by atransmitter.

601, the transmitter generates a plurality of channel estimationpreamble signals, wherein any two adjacent measurement signals of one ofthe plurality of channel estimation preamble signals are isolated by atleast one void subcarrier.

602, the transmitter sends the plurality of channel estimation preamblesignals via M transmitting antennas to N receiving antennas of a remotereceiver, wherein M and N are integers larger than 1.

In the embodiment of the present disclosure, by inserting a voidsubcarrier between measurement signals in the transmitted channelestimation preamble signals, inter-carrier interference during receptionat the receiver can be reduced.

Optionally, the sending, by the transmitter, the plurality of channelestimation preamble signals via the M transmitting antennas to the Nreceiving antennas of the remote receiver may include: sending, by thetransmitter via the M transmitting antennas in turns, the plurality ofchannel estimation preamble signals to the N receiving antennas of theremote receiver, wherein any two transmitting antennas in the Mtransmitting antennas do not simultaneously send the plurality ofchannel estimation preamble signals. By sending the channel estimationpreamble signals by the transmitting antennas in turns, inter-carrierinterference during reception at the receiver can be further reduced.

Optionally, a subcarrier set for sending a measurement signal of them^(th) transmitting antenna in the M transmitting antennas is equal to aset of subcarriers of the m^(th) transmitting antenna. By sending ameasurement signal within a range of carriers of a transmitting antenna,the receiver is enabled to obtain the channel estimation parameters andthe channel phase shift parameters over the full-band of thetransmitting antenna.

Optionally, the measurement signal may include a pilot signal.

FIG. 7 is a schematic diagram of a structure of a receiver 700 in anembodiment of the present disclosure. The receiver 700 may include adetermining unit 702 and N receiving antennas 701.

The N receiving antennas 701 may receive a plurality of channelestimation preamble signals sent by M transmitting antennas of a remotetransmitter.

The plurality of channel estimation preamble signals contain measurementsignals of the M transmitting antennas of the remote transmitter, and Mand N are integers larger than 1.

The determining unit 702 may determine channel estimation parameters andchannel phase shift parameters from the M transmitting antennas of theremote transmitter to the N receiving antennas 701 of the receiveraccording to the measurement signals of the M transmitting antennas ofthe remote transmitter.

The determining unit 702 may further determine signal compensation fromthe M transmitting antennas of the remote transmitter to the N receivingantennas of the receiver according to the channel estimation parametersand the channel phase shift parameters.

In the embodiment of the present disclosure, the receiver 700 determinesthe channel estimation parameters and the channel phase shift parametersaccording to the measurement signals of the remote transmitter, andfurther determines the signal compensation, thereby improving accuracyof an estimated value of transmitted data.

In FIG. 7, although the N receiving antennas are represented by only oneblock diagram, it does not mean that the N receiving antennas must be acomplete whole. The N receiving antennas may be a whole, or each of theN receiving antennas is an independent individual, or each of several ofthe N receiving antennas is an entirety, and no limitation is set hereinby the embodiment of the present disclosure.

Optionally, a subcarrier set for sending a measurement signal of them^(th) transmitting antenna in the M transmitting antennas is equal to aset of subcarriers of the m^(th) transmitting antenna, ∀m={1, . . . ,M}.By sending the measurement signal on the entire range of carriers of atransmitting antenna, the receiver at the receiving end is enabled toobtain channel estimation parameters and channel phase shift parametersof all the subcarriers of the transmitting antenna.

Optionally, the measurement signal may include a pilot signal. Ofcourse, a possibility of using other signal as the measurement signal isnot excluded.

Optionally, when determining the channel estimation parameters and thechannel phase shift parameters from the M transmitting antennas of theremote transmitter to the N receiving antennas 701 according to themeasurement signals of the M transmitting antennas of the remotetransmitter, the determining unit 702 may specifically determine atleast one channel estimation parameter and at least one channel phaseshift parameter for the k^(th) subcarrier of the m^(th) transmittingantenna according to at least one measurement signal on the k^(th)subcarrier of the m^(th) transmitting antenna, and determine an averagevalue of the at least one channel estimation parameter for the k^(th)subcarrier of the m^(th) transmitting antenna and an average value ofthe at least one channel phase shift parameter for the k^(th) subcarrierof the m^(th) transmitting antenna as a channel estimation parameter anda channel phase shift parameter for the k^(th) subcarrier of the m^(th)transmitting antenna, wherein the m^(th) transmitting antenna is one ofthe M transmitting antennas, ∀m={1, . . . ,M}.

Optionally, when determining the channel estimation parameters and thechannel phase shift parameters from the M transmitting antennas of theremote transmitter to the N receiving antennas 701 according to themeasurement signals of the M transmitting antennas of the remotetransmitter, the determining unit 702 may determine the channelestimation parameters from the M transmitting antennas of the remotetransmitter to the N receiving antennas 701 according to measurementsignals transmitted by the M transmitting antennas of the remotetransmitter and measurement signals received by the N receiving antennas701, and determine the channel phase shift parameters from the Mtransmitting antennas of the remote transmitter to the N receivingantennas 701 according to the measurement signals transmitted by the Mtransmitting antennas of the remote transmitter, the measurement signalsreceived by the N receiving antennas 701 and the channel estimationparameters from the M transmitting antennas of the remote transmitter tothe N receiving antennas 701.

Optionally, a formula for the determining unit 702 to determine thechannel estimation parameters from the M transmitting antennas of theremote transmitter to the N receiving antennas 701 according to themeasurement signals transmitted by the M transmitting antennas of theremote transmitter and the measurement signals transmitted by the Nreceiving antennas 701 is specifically shown in formula (18).

_(nm) ^(k) =y _(n) ^(k)(l)/s ^(k) , ∀n={1, . . . ,N},k∈K   (18)

where

_(nm) ^(k) represents a channel parameter for the k^(th) subcarrier fromthe m^(th) transmitting antenna of the remote transmitter to the n^(th)receiving antenna in the N receiving antennas 701, y_(n) ^(k)(l)represents a measurement signal received by the n^(th) receiving antennain the N receiving antennas 701, s^(k) represents a measurement signalsent on the K^(th) subcarrier by the remote transmitter, and Krepresents a subcarrier set of the m^(th) transmitting antenna of theremote transmitter.

A formula for the determining unit 702 to determine, according to themeasurement signals transmitted by the M transmitting antennas of theremote transmitter, the measurement signals received by the N receivingantennas 701 and the channel estimation parameters from the Mtransmitting antennas of the remote transmitter to the N receivingantennas 701, the channel phase shift parameters from the M transmittingantennas of the remote transmitter to the N receiving antennas 701, isspecifically shown in formula (19).

$\begin{matrix}{\begin{bmatrix}e^{j\;{\hat{\theta}}_{k_{1},l}} \\\vdots \\e^{j\;{\hat{\theta}}_{k_{M},l}}\end{bmatrix} = {{{\begin{bmatrix}s_{1}^{k} & \ldots & 0 \\\vdots & \vdots & \vdots \\0 & \cdots & s_{M}^{k}\end{bmatrix}\left\lbrack {\left\lbrack {\hat{H}}^{k} \right\rbrack^{\dagger}{\hat{H}}^{k}} \right\rbrack}^{- 1}\left\lbrack {\hat{H}}^{k} \right\rbrack}^{\dagger}\begin{bmatrix}{y_{1}^{k}(l)} \\\vdots \\{y_{N}^{k}(l)}\end{bmatrix}}} & (19)\end{matrix}$

where

represents a channel phase shift parameter of the m^(th) transmittingantenna of the remote transmitter, y_(n) ^(k)(l) represents ameasurement signal received by the n^(th) receiving antenna in the Nreceiving antennas 701, s_(m) ^(k) represents a measurement signaltransmitted on the k^(th) subcarrier by the m^(th) transmitting antennaof the remote transmitter, and [

^(k)]^(†) represents a conjugate matrix of

^(k), ∀m={1, . . . ,M}, ∀n={1, . . . ,N}.

Further, a formula for the determining unit 702 to determine the signalcompensation from the M transmitting antennas of the remote transmitterto the N receiving antennas 701 according to the channel estimationparameters and the channel phase shift parameters is specifically shownin formula (20).

$\begin{matrix}{\begin{bmatrix}{\hat{x}}_{1}^{d} \\\vdots \\{\hat{x}}_{M}^{d}\end{bmatrix} = {{{\begin{bmatrix}e^{{- j}\;{\overset{\sim}{\theta}\;}_{d_{1},l}} & \ldots & 0 \\\vdots & \vdots & \vdots \\0 & \ldots & e^{{- j}\;{\overset{\sim}{\theta}\;}_{d_{M},l}}\end{bmatrix}\left\lbrack {\left\lbrack {\hat{H}}^{d} \right\rbrack^{\dagger}{\hat{H}}^{d}} \right\rbrack}^{- 1}\left\lbrack {\hat{H}}^{d} \right\rbrack}^{\dagger}\begin{bmatrix}{y_{1}^{d}(l)} \\\vdots \\{y_{N}^{d}(l)}\end{bmatrix}}} & (20)\end{matrix}$

where {circumflex over (x)}_(m) ^(d) represents a quadrature amplitudemodulation (QAM) signal of the d^(th) subcarrier transmitted by them^(th) transmitting antenna.

In addition, the receiver 700 may also execute the method in FIG. 1 andimplement the functions of the receiver in the embodiment shown in FIG.1, which will not be described redundantly herein in the embodiment ofthe present disclosure.

FIG. 8 is a schematic diagram of a structure of a receiver 800 in anembodiment of the present disclosure. The receiver 800 may include aprocessor 802, a memory 803 and N receiving antennas 801.

The N receiving antennas 801 may receive a plurality of channelestimation preamble signals sent by M transmitting antennas of a remotetransmitter.

The plurality of channel estimation preamble signals contain measurementsignals of the M transmitting antennas of the remote transmitter, and Mand N are integers larger than 1.

The processor 802 may determine channel estimation parameters andchannel phase shift parameters from the M transmitting antennas of theremote transmitter to the N receiving antennas 801 of the receiveraccording to the measurement signals of the M transmitting antennas ofthe remote transmitter, and determine signal compensation from the Mtransmitting antennas of the remote transmitter to the N receivingantennas of the receiver according to the channel estimation parametersand the channel phase shift parameters.

The memory 803 may store an instruction for the processor 802 todetermine the channel estimation parameters and the channel phase shiftparameters from the M transmitting antennas of the remote transmitter tothe N receiving antennas 801 of the receiver according to themeasurement signals of the M transmitting antennas of the remotetransmitter, and determine the signal compensation from the Mtransmitting antennas of the remote transmitter to the N receivingantennas of the receiver according to the channel estimation parametersand the channel phase shift parameters.

In the embodiment of the present disclosure, the receiver 800 determinesthe channel estimation parameters and the channel phase shift parametersaccording to the measurement signals of the remote transmitter, so as todetermine the signal compensation and improve accuracy of an estimatedvalue of transmitted data.

The processor 802 controls an operation of the receiver 800, and theprocessor 802 may also be referred to as a CPU (central processingunit). The memory 803 may include a read-only memory and a random accessmemory, and provide an instruction and data to the processor 802. A partof the memory 803 may further include a nonvolatile random access memory(NVRAM). Respective components of the receiver 800 are coupled togetherby a bus system 806, wherein besides a data bus, the bus system 806 mayfurther include a power source bus, a control bus, a status signal busand the like. But for clarity of illustration, various buses in thefigure are marked as the bus system 806.

The method disclosed in the above-mentioned embodiment of the presentdisclosure may be applied to the processor 802, or may be implemented bythe processor 802. The processor 802 may be an integrated circuit chipwith a signal processing capability. In an implementation process, therespective steps of the above-mentioned method may be completed by anintegrated logic circuit of hardware in the processor 802 or aninstruction in a form of software. The above-mentioned processor 802 maybe a general-purpose processor, a digital signal processor (DSP), anapplication-specific integrated circuit (ASIC), a field-programmablegate array (FPGA) or other programmable logic device, a discrete gate ora transistor logic device, or a discrete hardware component, and mayimplement or execute respective methods, steps and logic block diagramsdisclosed in the embodiment of the present disclosure. Thegeneral-purpose processor may be a microprocessor or may be anyconventional processor or the like. The steps of the method disclosed inthe embodiment of the present disclosure may be directly executed andcompleted by a hardware decoding processor, or is executed and completedby a combination of hardware and software modules in the decodingprocessor. The software module may be located in a mature storage mediumin the art, such as a random access memory, a flash memory, a read-onlymemory, a programmable read-only memory or an electrically erasableprogrammable memory, a register, etc. The storage medium is located inthe memory 803, and the processor 802 reads the information in thememory 803 and completes the steps of the above-mentioned method incombination with the hardware thereof.

Optionally, a subcarrier set for sending a measurement signal of them^(th) transmitting antenna in the M transmitting antennas is equal to aset of subcarriers of the M^(th) transmitting antenna. By sending themeasurement signal on the entire range of carriers of a transmittingantenna, the receiver at the receiving end may obtain the channelestimation parameters and the channel phase shift parameters of all thesubcarriers of the transmitting antenna.

Optionally, the measurement signal may include a pilot signal. Ofcourse, a possibility of using other signal as the measurement signal isnot excluded.

Optionally, when determining the channel estimation parameters and thechannel phase shift parameters from the M transmitting antennas of theremote transmitter to the N receiving antennas 801 according to themeasurement signals of the M transmitting antennas of the remotetransmitter, the processor 802 may specifically determine at least onechannel estimation parameter and at least one channel phase shiftparameter of the m^(th) transmitting antenna on the k^(th) subcarrieraccording to at least one measurement signal of the m^(th) transmittingantenna on the k^(th) subcarrier, and determine an average value of theat least one channel estimation parameter and an average value of the atleast one channel phase shift parameter of the m^(th) transmittingantenna on the k^(th) subcarrier as the channel estimation parameter andthe channel phase shift parameter of the m^(th) transmitting antenna onthe k^(th) subcarrier, wherein the m^(th) transmitting antenna is one ofthe M transmitting antennas, ∀m={1, . . . ,M}.

Optionally, when determining the channel estimation parameters and thechannel phase shift parameters from the M transmitting antennas of theremote transmitter to the N receiving antennas 801 according to themeasurement signals of the M transmitting antennas of the remotetransmitter, the processor 802 may determine the channel estimationparameters from the M transmitting antennas of the remote transmitter tothe N receiving antennas 801 according to measurement signalstransmitted by the M transmitting antennas of the remote transmitter andmeasurement signals received by the N receiving antennas 801, anddetermine the channel phase shift parameters from the M transmittingantennas of the remote transmitter to the N receiving antennas 801according to the measurement signals transmitted by the M transmittingantennas of the remote transmitter, the measurement signals received bythe N receiving antennas of the receiver, and the channel estimationparameters from the M transmitting antennas of the remote transmitter tothe N receiving antennas 801.

Optionally, a formula for the processor 802 to determine the channelestimation parameters from the M transmitting antennas of the remotetransmitter to the N receiving antennas 801 according to measurementsignals transmitted by the M transmitting antennas of the remotetransmitter and measurement signals received by the N receiving antennas801 is specifically as shown in formula (21).

_(nm) ^(k) =y _(n) ^(k)(l)/s ^(k) , ∀n={1, . . . ,N},k∈K   (21)

where

_(nm) ^(k) represents a channel parameter on the k^(th) subcarrier fromthe m^(th) transmitting antenna of the remote transmitter to the n^(th)receiving antenna in the N receiving antennas 801, y_(n) ^(k)(l)represents a measurement signal received by the n^(th) receiving antennain the N receiving antennas 801, s^(k) represents a measurement signalsent on the k^(th) subcarrier by the remote transmitter, and Krepresents a set of subcarriers of the m^(th) transmitting antenna ofthe remote transmitter.

A formula for the processor 802 to determine the channel phase shiftparameters from the M transmitting antennas of the remote transmitter tothe N receiving antennas 801 according to the measurement signalstransmitted by the M transmitting antennas of the remote transmitter,the measurement signals received by the N receiving antennas of thereceiver, and the channel estimation parameters from the M transmittingantennas of the remote transmitter to the N receiving antennas 801 isspecifically as shown in formula (22).

$\begin{matrix}{\begin{bmatrix}e^{j\;{\hat{\theta}}_{k_{1},l}} \\\vdots \\e^{j\;{\hat{\theta}}_{k_{M},l}}\end{bmatrix} = {{{\begin{bmatrix}s_{1}^{k} & \ldots & 0 \\\vdots & \vdots & \vdots \\0 & \ldots & s_{M}^{k}\end{bmatrix}\left\lbrack {\left\lbrack {\hat{H}}^{k} \right\rbrack^{\dagger}{\hat{H}}^{k}} \right\rbrack}^{- 1}\left\lbrack {\hat{H}}^{k} \right\rbrack}^{\dagger}\begin{bmatrix}{y_{1}^{k}(l)} \\\vdots \\{y_{N}^{k}(l)}\end{bmatrix}}} & (22)\end{matrix}$

where e^(j{circumflex over (θ)}) ^(km,l) represents a channel phaseshift parameter of the m^(th) transmitting antenna of the remotetransmitter, y_(n) ^(k)(l) represents a measurement signal received bythe n^(th) receiving antenna in the N receiving antennas 801, s_(m) ^(k)represents a measurement signal transmitted on the k^(th) subcarrier bythe m^(th) transmitting antenna of the remote transmitter, and [

^(k)]^(†) represents a conjugate matrix of

^(k), ∀n={1, . . . ,N}.

Further, a formula for the processor 802 to determine the signalcompensation from the M transmitting antennas of the remote transmitterto the N receiving antennas 801 according to the channel estimationparameters and the channel phase shift parameters is specifically asshown in formula (23).

$\begin{matrix}{\begin{bmatrix}{\hat{x}}_{1}^{d} \\\vdots \\{\hat{x}}_{M}^{d}\end{bmatrix} = {{{\begin{bmatrix}e^{{- j}\;{\overset{\sim}{\theta}\;}_{d_{1},l}} & \ldots & 0 \\\vdots & \vdots & \vdots \\0 & \ldots & e^{{- j}\;{\overset{\sim}{\theta}\;}_{d_{M},l}}\end{bmatrix}\left\lbrack {\left\lbrack {\hat{H}}^{d} \right\rbrack^{\dagger}{\hat{H}}^{d}} \right\rbrack}^{- 1}\left\lbrack {\hat{H}}^{d} \right\rbrack}^{\dagger}\begin{bmatrix}{y_{1}^{d}(l)} \\\vdots \\{y_{N}^{d}(l)}\end{bmatrix}}} & (23)\end{matrix}$

where {circumflex over (x)}_(m) ^(d) represents a quadrature amplitudemodulation (QAM) signal on the d^(th) subcarrier transmitted by them^(th) transmitting antenna.

In addition, the receiver 800 may also execute the method in FIG. 1 andimplement the functions of the receiver in the embodiment shown in FIG.1, which will not be described in detain redundantly herein in theembodiment of the present disclosure.

FIG. 9 is a schematic diagram of a structure of an MIMO-OFDM system 900in an embodiment of the present disclosure. The MIMO-OFDM system 900 mayinclude a transmitter 901 and a receiver 902.

The receiver 902 may be the receiver 700 shown in FIG. 7 or the receiver800 shown in FIG. 8. The transmitter 901 is used for sending, via Mtransmitting antennas in turns, a plurality of channel estimationpreamble signals to N receiving antennas of the receiver 902. Theplurality of channel estimation preamble signals contain measurementsignals of the M transmitting antennas of the transmitter 901, where Mand N are integers larger than 1.

In the embodiment of the present disclosure, the MIMO-OFDM system 900determines channel estimation parameters and channel phase shiftparameters according to the measurement signals of the remotetransmitter, and further determines signal compensation for thereceiving end, thereby improving accuracy of an estimated value oftransmitted data.

Optionally, a subcarrier set for sending a measurement signal of them^(th) transmitting antenna in the M transmitting antennas is equal to aset of subcarriers of the m^(th) transmitting antenna, where ∀m={1, . .. ,M}. By sending the measurement signal on an entire range of carriersof one transmitting antenna, a receiver at a receiving end is enabled toobtain the channel estimation parameters and the channel phase shiftparameters of all subcarriers of the transmitting antenna.

Optionally, the measurement signal may include a pilot signal. Ofcourse, a possibility of using other signal as the measurement signal isnot excluded.

Optionally, any two adjacent measurement signals of one of the pluralityof channel estimation preamble signals are isolated by at least one voidsubcarrier, and the void subcarrier is used for reducing inter-carrierinterference (ICI) during reception at the receiver.

Optionally, any two transmitting antennas in the M transmitting antennasdo not simultaneously send the plurality of channel estimation preamblesignals.

In the embodiment as shown in FIG. 1, specifically, prior to step 102and after step 101, the method may further include: receiving, by thereceiver via the N receiving antennas, data signals and second pilotsignals sent on a first data symbol by the M transmitting antennas. Step102 may be specifically implemented as follows: the receiver determinesthe channel estimation parameters from the M transmitting antennas tothe N receiving antennas according to first pilot signals of the Mtransmitting antennas contained in the plurality of channel estimationpreamble signals, and determines the channel phase shift parameters fromthe M transmitting antennas to the N receiving antennas according tosignals arrived at the N receiving antennas which come from the secondpilot signals sent on the first data symbol by the M transmittingantennas. Step 103 may be specifically implemented as follows: thereceiver determines the signal compensation for the data signals arrivedat the N receiving antennas that are sent on the first data symbol bythe M transmitting antennas according to the channel estimationparameters from the M transmitting antennas to the N receiving antennasand the channel phase shift parameters from the M transmitting antennasto the N receiving antennas. In this case, the method in the embodimentof the present disclosure may be as shown in FIG. 10.

FIG. 10 is a flowchart of a method for signal compensation in anembodiment of the present disclosure. The method shown in FIG. 10 isexecuted by a receiver. The receiver mentioned herein refers to areceiving end device of an MIMO-OFDM system, and may be a base station,a mobility management entity (MME), a gateway or other network element,which is not limited in the embodiment of the present disclosure. Themethod includes the following steps.

1001, the receiver receives, via N receiving antennas, a plurality ofchannel estimation preamble signals sent by M transmitting antennas of aremote transmitter.

The plurality of channel estimation preamble signals contain first pilotsignals of the M transmitting antennas, and M and N are integers largerthan 1.

1002, the receiver determines channel estimation parameters from the Mtransmitting antennas to the N receiving antennas according to the firstpilot signals of the M transmitting antennas contained in the pluralityof channel estimation preamble signals.

1003, the receiver receives, via the N receiving antennas, data signalsand second pilot signals sent on a first data symbol by the Mtransmitting antennas.

1004, the receiver determines channel phase shift parameters from the Mtransmitting antennas to the N receiving antennas according to signalsarrived at the N receiving antennas which come from the second pilotsignals sent on the first data symbol by the M transmitting antennas.

1005, the receiver determines, according to the channel estimationparameters from the M transmitting antennas to the N receiving antennasand the channel phase shift parameters from the M transmitting antennasto the N receiving antennas, signal compensation for the data signalsarrived at the N receiving antennas that are sent on the first datasymbol by the M transmitting antennas.

In the embodiment of the present disclosure, the receiver determines thesignal compensation of the data signals according to the channelestimation parameters from the transmitting antennas of the remotetransmitter to the receiving antennas of the receiver and the channelphase shift parameters of the transmitting antennas of the remotetransmitter on the first data symbol, which can improve demodulationaccuracy of transmitted data to a certain extent.

Optionally, a subcarrier set for sending a first pilot signal of them^(th) transmitting antenna in the M transmitting antennas is equal to aset of subcarriers of the m^(th) transmitting antenna, ∀m={1, . . . ,M}.

Optionally, as one embodiment, the N receiving antennas are coherent,and the M transmitting antennas are coherent.

In an embodiment where both the receiver and the transmitter arecoherent, step 1004 may be implemented as follows: the receiverdetermines, according to a signal arrived at the N receiving antennaswhich comes from a second pilot signal sent on the first data symbol bythe m^(th) transmitting antenna in the M transmitting antennas, channelphase shift parameters from the m^(th) transmitting antenna in the Mtransmitting antennas to the N receiving antennas, where ∀m={1, . . .,M}.

Further, the determining, by the receiver, the channel phase shiftparameters from the m^(th) transmitting antenna in the M transmittingantennas to the N receiving antennas, according to the signal arrived atthe N receiving antennas which comes from the second pilot signal senton the first data symbol by the m^(th) transmitting antenna in the Mtransmitting antennas, may be specifically implemented as follows: ifthere is more than one subcarrier on the first data symbol for sendingthe second pilot signal, determining, by the receiver according tosignals arrived at the N receiving antennas which come from the secondpilot signals sent on a plurality of subcarriers of the first datasymbol by the m^(th) transmitting antenna in the M transmittingantennas, multiple groups of channel phase shift parameters from them^(th) transmitting antenna in the M transmitting antennas to the Nreceiving antennas, and determining average values of the multiplegroups of channel phase shift parameters as the channel phase shiftparameters from the m^(th) transmitting antenna in the M transmittingantennas to the N receiving antennas.

In this case, step 1005 may be expressed by the following formula (24).

$\begin{matrix}{\begin{bmatrix}{\hat{x}}_{1}^{k} \\\vdots \\{\hat{x}}_{M}^{k}\end{bmatrix} = {{{\begin{bmatrix}e^{{- j}\;{\overset{\sim}{\theta}\;}_{k_{1},l}} & \ldots & 0 \\\vdots & \vdots & \vdots \\0 & \ldots & e^{{- j}\;{\overset{\sim}{\theta}\;}_{k_{M},l}}\end{bmatrix}\left\lbrack {\left\lbrack {\hat{H}}^{k} \right\rbrack^{\dagger}{\hat{H}}^{k}} \right\rbrack}^{- 1}\left\lbrack {\hat{H}}^{k} \right\rbrack}^{\dagger}\begin{bmatrix}{y_{1}^{k}(l)} \\\vdots \\{y_{N}^{k}(l)}\end{bmatrix}}} & (24)\end{matrix}$

wherein, {circumflex over (x)}_(m) ^(k) represents a data signalobtained from a demodulation performed by the receiver that istransmitted on the k^(th) subcarrier of the l^(th) data symbol by them^(th) transmitting antenna, y_(n) ^(k)(l) represents a pilot signalarrived at the n^(th) receiving antenna of the receiver which comes froma data signal transmitted on the k^(th) subcarrier of the 1^(th) datasymbol by the M transmitting antennas, ∀m={1, . . . ,M}, ∀n={1, . . .,N},

^(k) represents a channel estimation parameter matrix on the k^(th)subcarrier between the M transmitting antennas and the N receivingantennas, [

^(k)]^(†) represents a conjugate matrix of

^(k),

_(nm) ^(k) in

^(k) represents a channel estimation parameter on the k^(th) subcarrierbetween the m^(th) transmitting antenna of the remote transmitter andthe n^(th) receiving antenna of the receiver, and

_(nm) ^(k) may be expressed by formula (25).

_(nm) ^(k) =y _(n) ^(k)(t)/s ^(k) , ∀n={1, . . . ,N},k∈K   (25)

where K represents a subcarrier set of the m^(th) transmitting antennaof the remote transmitter for transmitting the channel estimationpreamble signal, s^(k) represents a pilot signal of the k^(th)subcarrier in the plurality of channel estimation preamble signals,y_(n) ^(k)(t) represents a pilot signal arrived at the n^(th) receivingantenna of the receiver which comes from a pilot signal on the k^(th)subcarrier in the t^(th) channel estimation preamble signal of theremote transmitter,

$\quad\begin{bmatrix}e^{j\;{\hat{\theta}}_{k_{1},l}} \\\vdots \\e^{j\;{\hat{\theta}}_{k_{M},l}}\end{bmatrix}$represents channel phase shift parameters for signals arrived at the Nreceiving antennas which are sent on the k^(th) subcarrier of the datasymbol by the M transmitting antennas, and

$\quad\begin{bmatrix}e^{j\;{\hat{\theta}}_{k_{1},l}} \\\vdots \\e^{j\;{\hat{\theta}}_{k_{M},l}}\end{bmatrix}$may be expressed by formula (26).

$\begin{matrix}{\begin{bmatrix}e^{j\;{\hat{\theta}}_{k_{1},l}} \\\vdots \\e^{j\;{\hat{\theta}}_{k_{M},l}}\end{bmatrix} = {{{\begin{bmatrix}s_{1}^{k} & \ldots & 0 \\\vdots & \vdots & \vdots \\0 & \ldots & s_{M}^{k}\end{bmatrix}\left\lbrack {\left\lbrack H^{k} \right\rbrack^{\dagger}H^{k}} \right\rbrack}^{- 1}\left\lbrack H^{k} \right\rbrack}^{\dagger}\begin{bmatrix}{y_{1}^{k}(l)} \\\vdots \\{y_{N}^{k}(l)}\end{bmatrix}}} & (26)\end{matrix}$

where s_(m) ^(k) represents a pilot signal transmitted on the k^(th)subcarrier by the m^(th) transmitting antenna of the remote transmitter,y_(n) ^(k)(l) represents a pilot signal arrived at the n^(th) receivingantenna of the receiver which comes from a pilot signal sent on thek^(th) subcarrier of the 1^(th) data symbol by the M transmittingantennas, and

represents a channel phase shift parameter for the signal arrived at theN receiving antennas that is sent on the k^(th) subcarrier of the l^(th)data symbol by the m^(th) transmitting antenna of the remotetransmitter.

Optionally, as another embodiment, the N receiving antennas areincoherent, and/or the M transmitting antennas are incoherent.

Optionally, in an embodiment where the receiver and/or the transmitteris incoherent, step 1004 may be implemented as follows: the receiverdetermines the channel phase shift parameters from the M transmittingantennas to the N receiving antennas according to all of pilot signalsarrived at the N receiving antennas which come from the second pilotsignals sent on the first data symbol by the M transmitting antennas,wherein a quantity of pilot subcarriers where all the pilot signals arelocated is not smaller than M.

In this case, step 1005 may be expressed by the following formula (27):

$\begin{matrix}{\begin{bmatrix}{\hat{x}}_{1}^{k} \\\vdots \\{\hat{x}}_{M}^{k}\end{bmatrix} = {{\left\lbrack {\left\lbrack {\hat{H}}_{\xi}^{k} \right\rbrack^{\dagger}{\hat{H}}_{\xi}^{k}} \right\rbrack^{- 1}\left\lbrack {\hat{H}}_{\xi}^{k} \right\rbrack}^{\dagger}\begin{bmatrix}{y_{1}^{k}(l)} \\\vdots \\{y_{N}^{k}(l)}\end{bmatrix}}} & (27)\end{matrix}$

wherein {circumflex over (x)}_(m) ^(k) represents a data signal obtainedfrom a demodulation performed by the receiving terminal that istransmitted on the k^(th) subcarrier of the l^(th) data symbol by them^(th) transmitting antenna, y_(n) ^(k)(l) represents a signal arrivedat the n^(th) receiving antenna of the receiver which comes from a datasignal transmitted on the k^(th) subcarrier of the 1^(th)data symbol bythe M transmitting antennas, ∀m={1, . . . ,M}, ∀n={1, . . . ,N}, [

_(ξ) ^(k)]^(†) represents a conjugate matrix of

_(ξ) ^(k), and

_(ξ) ^(k) may be expressed by formula (28).

$\begin{matrix}{H_{\xi}^{k} = \begin{bmatrix}{{\hat{H}}_{11}^{k}e^{j\;\xi_{11}}} & \ldots & {{\hat{H}}_{1M}^{k}e^{j\;\xi_{1M}}} \\\vdots & \vdots & \vdots \\{{\hat{H}}_{N\; 1}^{k}e^{j\;\xi_{N\; 1}}} & \ldots & {{\hat{H}}_{N\; M}^{k}e^{j\;\xi_{N\; M}}}\end{bmatrix}} & (28)\end{matrix}$

_(nm) ^(k) in

_(ξ) ^(k) represents a channel estimation parameter on the k^(th)subcarrier between the m^(th) transmitting antenna of the remotetransmitter and the n^(th) receiving antenna of the receiver, and may beexpressed by formula (29).

_(nm) ^(k) =y _(n) ^(k)(t)/ s ^(k) , ∀n={1, . . . ,N},k∈K   (29)

where K represents a subcarrier set of the m^(th) transmitting antennaof the remote transmitter for transmitting the channel estimationpreamble signal, s^(k) represents a pilot signal of the k^(th)subcarrier in the plurality of channel estimation preamble signals,y_(n) ^(k)(t) represents a pilot signal arrived at the n^(th) receivingantenna of the receiver which comes from a pilot signal on the k^(th)subcarrier in the t^(th) channel estimation preamble signal of theremote transmitter,

$\quad\begin{bmatrix}e^{j\;\xi_{11}} & \ldots & e^{j\;\xi_{1M}} \\\vdots & \vdots & \vdots \\e^{j\;\xi_{N\; 1}} & \ldots & e^{j\;\xi_{N\; M}}\end{bmatrix}$represents channel phase shift parameters for signals arrived at the Nreceiving antennas that are sent on the 1^(th) data symbol by the Mtransmitting antennas, and

$\quad\begin{bmatrix}e^{j\;\xi_{11}} & \ldots & e^{j\;\xi_{1M}} \\\vdots & \vdots & \vdots \\e^{j\;\xi_{N\; 1}} & \ldots & e^{j\;\xi_{N\; M}}\end{bmatrix}$may be expressed by formula (30).

$\begin{matrix}{\begin{bmatrix}e^{j\;\xi_{\;_{11}}} & \ldots & e^{j\;\xi_{\;_{1M}}} \\\vdots & \vdots & \vdots \\e^{j\;\xi_{\;_{N\; 1}}} & \ldots & e^{j\;\xi_{\;_{N\; M}}}\end{bmatrix} = {{\left\lbrack {\begin{bmatrix}{\overset{\sim}{H}}^{p_{1}} \\\vdots \\{\overset{\sim}{H}}^{p_{|p|}}\end{bmatrix}^{\dagger}\begin{bmatrix}{\overset{\sim}{H}}^{p_{1}} \\\vdots \\{\overset{\sim}{H}}^{p_{|p|}}\end{bmatrix}} \right\rbrack^{- 1}\begin{bmatrix}{\overset{\sim}{H}}^{p_{1}} \\\vdots \\{\overset{\sim}{H}}^{p_{|p|}}\end{bmatrix}}^{\dagger}\begin{bmatrix}{y_{1}^{P_{1}}(l)} \\\vdots \\{y_{N}^{P_{1}}(l)} \\{y_{1}^{P_{2}}(l)} \\\vdots \\{y_{N}^{P_{p}}(l)}\end{bmatrix}}} & (30)\end{matrix}$

where y_(n) ^(p)(l) represents a pilot signal arrived at the N receivingantennas which comes from a pilot signal transmitted on a pilotsubcarrier p of the l^(th) data symbol by the M transmitting antennas, prepresents any pilot subcarrier in a pilot subcarrier set {p₁, . . .p_(|p|)} of the l^(th) data symbol, and

^(p) may be expressed by formula (31).

            (31) ${\overset{\sim}{H}}^{p} = {\quad\begin{bmatrix}{{\hat{H}}_{11}^{p}s_{1}^{p}} & \ldots & {{\hat{H}}_{1M}^{p}s_{M}^{p}} & 0 & \ldots & 0 & 0 & \ldots & 0 \\0 & \ldots & 0 & {{\hat{H}}_{21}^{p}s_{1}^{p}} & \ldots & {{\hat{H}}_{2M}^{p}s_{M}^{p}} & \vdots & \ldots & \vdots \\\vdots & \ldots & \vdots & \vdots & \vdots & \vdots & 0 & \ldots & 0 \\0 & \ldots & 0 & 0 & \ldots & 0 & {{\hat{H}}_{N\; 1}^{p}s_{1}^{p}} & \ldots & {{\hat{H}}_{N\; M}^{p}s_{M}^{p}}\end{bmatrix}}$

Optionally, in another embodiment where the receiver and/or thetransmitter is incoherent, step 1004 may be implemented as follows: thereceiver determines, according to at least one group of pilot signalsarrived at the n^(th) receiving antenna in the N receiving antennaswhich come from the second pilot signals sent on the first data symbolby the M transmitting antennas, channel phase shift parameters from theM transmitting antennas to the n^(th) receiving antenna in the Nreceiving antennas, wherein each group of pilot signals in the at leastone group of pilot signals contains pilot signals received on J numbersof subcarriers by the N receiving antennas, and a value of J is notsmaller than M.

In this case, step 1005 may be expressed by the following formula (32):

$\begin{matrix}{\begin{bmatrix}{\hat{x}}_{1}^{k} \\\vdots \\{\hat{x}}_{M}^{k}\end{bmatrix} = {{\left\lbrack {\left\lbrack {\hat{H}}_{\xi}^{k} \right\rbrack^{\dagger}{\hat{H}}_{\xi}^{k}} \right\rbrack^{- 1}\left\lbrack {\hat{H}}_{\xi}^{k} \right\rbrack}^{\dagger}\begin{bmatrix}{y_{1}^{k}(l)} \\\vdots \\{y_{N}^{k}(l)}\end{bmatrix}}} & (32)\end{matrix}$

where {circumflex over (x)}_(m) ^(k) represents a data signal obtainedby a receiving terminal by demodulation that is transmitted on thek^(th) subcarrier of the l^(th) data symbol by the m^(th) transmittingantenna, y_(n) ^(k)(l) represents a pilot signal arrived at the n^(th)receiving antenna of the receiver which comes from a pilot signal senton the k^(th) subcarrier of the 1^(th) data symbol by the M transmittingantennas, ∀m={1, . . . ,M}, ∀n={1, . . . ,N}, [

_(ξ) ^(k)]^(†) represents a conjugate matrix of

_(ξ) ^(k), and

_(ξ) ^(k) may be expressed by formula (33).

$\begin{matrix}{{\hat{H}}_{\xi}^{k} = \begin{bmatrix}{{\hat{H}}_{11}^{k}e^{j\;\xi_{11}}} & \ldots & {{\hat{H}}_{1M}^{k}e^{j\;\xi_{1M}}} \\\vdots & \vdots & \vdots \\{{\hat{H}}_{N\; 1}^{k}e^{j\;\xi_{N\; 1}}} & \ldots & {{\hat{H}}_{N\; M}^{k}e^{j\;\xi_{N\; M}}}\end{bmatrix}} & (33)\end{matrix}$

_(nm) ^(k) in

_(ξ) ^(k) represents the channel estimation parameter between the m^(th)transmitting antenna of the remote transmitter and the n^(th) receivingantenna of the receiver on the k^(th) subcarrier, and may he expressedby formula (34):

_(nm) ^(k) =y _(n) ^(k)(t)/s ^(k) , ∀n={1, . . . ,N},k∈K   (34)

where K represents a subcarrier set of the m^(th) transmitting antennaof the remote transmitter for transmitting the channel estimationpreamble signal, s^(k) represents a pilot signal of the k^(th)subcarrier in the plurality of channel estimation preamble signals,y_(n) ^(k)(t) represents a pilot signal arrived at the n^(th) receivingantenna of the receiver which comes from a pilot signal on the k^(th)subcarrier in the t^(th) channel estimation preamble signal of theremote transmitter, e^(jξ) ^(n) represents a channel phase shiftparameter from the M transmitting antennas to the n^(th) receivingantenna in the N receiving antennas, and may be expressed by formula(35).

$\begin{matrix}{e^{j\;\xi\; n} = {\left\lbrack {\begin{bmatrix}{{\hat{H}}_{n\; 1}^{J_{1}}s_{1}^{J_{1}}} & \ldots & {{\hat{H}}_{n\; M}^{J_{1}}s_{M}^{J_{1}}} \\\vdots & \ldots & \vdots \\{{\hat{H}}_{n\; 1}^{J_{J}}s_{1}^{J_{J}}} & \ldots & {{\hat{H}}_{n\; M}^{J_{J}}s_{M}^{J_{J}}}\end{bmatrix}^{\dagger}\begin{bmatrix}{{\hat{H}}_{n\; 1}^{J_{1}}s_{1}^{J_{1}}} & \ldots & {{\hat{H}}_{n\; M}^{J_{1}}s_{M}^{J_{1}}} \\\vdots & \ldots & \vdots \\{{\hat{H}}_{n\; 1}^{J_{J}}s_{1}^{J_{J}}} & \ldots & {{\hat{H}}_{n\; M}^{J_{J}}s_{M}^{J_{J}}}\end{bmatrix}} \right\rbrack^{- 1}{\quad{\begin{bmatrix}{{\hat{H}}_{n\; 1}^{J_{1}}s_{1}^{J_{1}}} & \ldots & {{\hat{H}}_{n\; M}^{J_{1}}s_{M}^{J_{1}}} \\\vdots & \ldots & \vdots \\{{\hat{H}}_{n\; 1}^{J_{J}}s_{1}^{J_{J}}} & \ldots & {{\hat{H}}_{n\; M}^{J_{J}}s_{M}^{J_{J}}}\end{bmatrix}^{\dagger}\begin{bmatrix}{y_{n\;}^{J_{1}}(l)} \\\vdots \\{y_{n\;}^{J_{J}}(l)}\end{bmatrix}}}}} & (35)\end{matrix}$

where y_(n) ^(J)(l) represents a pilot signal arrived at the n^(th)receiving antenna in the N receiving antennas which comes from a pilotsignal transmitted on the pilot subcarrier J of the l^(th) data symbolby the M transmitting antennas, J represents any pilot subcarrier in apilot subcarrier set {J₁, . . . J_(|J|)} of the l^(th) data symbol, ands_(m) ^(J) represents a pilot signal transmitted on the pilot subcarrierJ of the l^(th) data symbol by the m^(th) transmitting antenna in the Mtransmitting antennas.

Further, the determining, by the receiver according to at least onegroup of pilot signals arrived at the n^(th) receiving antenna in the Nreceiving antennas which come from the second pilot signals sent on thefirst data symbol by the M transmitting antennas, channel phase shiftparameters from the M transmitting antennas to the n^(th) receivingantenna in the N receiving antennas, may be specifically implemented asfollows: the receiver determines multiple groups of channel phase shiftparameters from the M transmitting antennas to the n^(th) receivingantenna in the N receiving antennas according to multiple groups ofpilot signals arrived at the nth receiving antenna in the N receivingantennas which come from the second pilot signals sent on the first datasymbol by the M transmitting antennas, and determines an average valueof channel phase shift parameters in the multiple groups of channelphase shift parameters corresponding to a channel phase shift parameterfrom the m^(th) transmitting antenna in the M transmitting antennas tothe n^(th) receiving antenna in the N receiving antennas as a channelphase shift parameter from the m^(th) transmitting antenna in the Mtransmitting antennas to the n^(th) receiving antenna in the N receivingantennas.

Optionally, any two adjacent measurement signals of one of the pluralityof channel estimation preamble signals are isolated by at least one voidsubcarrier. No matter in an application scenario where both the receiverand the transmitter are coherent, or in an application scenario wherethe receiver and/or the transmitter is incoherent, the transmitting endinserts the void subcarrier into channel estimation preamble symbols toreduce inter-carrier interference (ICI), and the receiving end mayobtain a more accurate channel estimation parameter by utilizing asimple channel estimation method.

The methods in FIG. 1 and FIG. 10 may be applicable to the scenario withcoherent receiving and sending, such as, for example, embodiments one tothree in the present disclosure. In addition, the methods in FIG. 1 andFIG. 10 may also be applicable to the scenario with non-coherentreceiving and sending. An application of the methods in FIG. 1 and FIG.10 in the scenario with non-coherent receiving and sending will bedescribed below in detail in combination with specific embodiments.

In embodiment four of the present disclosure, the N receiving antennasof the receiver are incoherent, or the M transmitting antennas of theremote transmitter are incoherent, or the N receiving antennas of thereceiver and the M transmitting antennas of the remote transmitter areincoherent. It is assumed that the transmitter of the MIMO-OFDM systemsends the l^(th) channel estimation preamble signal on the m^(th)transmitting antenna, where a pilot signal in the channel estimationpreamble signal is used as the measurement signal, a subcarrier set forsending the pilot signal is K, then on the k^(th) subcarrier, where k∈K,signals of the N receiving antennas may be expressed by formula (36).

$\begin{matrix}{\begin{matrix}{{\begin{bmatrix}{y_{1}^{k}(l)} \\\vdots \\{y_{N}^{k}(l)}\end{bmatrix} = {\begin{bmatrix}e^{j\;\varphi_{1}} & \ldots & 0 \\\vdots & \ldots & \vdots \\0 & \ldots & e^{j\;\varphi_{N}}\end{bmatrix}\underset{\underset{H^{k}}{︸}}{\begin{bmatrix}H_{11}^{k} & \ldots & H_{1M}^{k} \\\vdots & \ldots & \vdots \\H_{N\; 1}^{k} & \ldots & H_{NM}^{k}\end{bmatrix}}}}\;} \\{{\begin{bmatrix}0 \\\vdots \\0 \\{e^{j\;\theta_{m}}s^{k}} \\0 \\\vdots \\0\end{bmatrix} + {ICI} + z}} \\{= {\begin{bmatrix}{H_{1m}^{k}e^{j{({\varphi_{1} + \theta_{m}})}}s^{k}} \\\vdots \\{H_{Nm}^{k}e^{j{({\varphi_{N} + \theta_{m}})}}s^{k}}\end{bmatrix} + {ICI}_{l} + z_{l}}}\end{matrix}{{{where}\mspace{14mu}\begin{bmatrix}{y_{1}^{k}(l)} \\\vdots \\{y_{N}^{k}(l)}\end{bmatrix}}\quad}} & (36)\end{matrix}$represents the l^(th) channel estimation preamble signal received by theN receiving antennas of the receiver; on the k^(th) subcarrier, receivedon the k^(th) subcarrier by the N receiving antennas of the receiver;

$\underset{\underset{H^{k}}{︸}}{\begin{bmatrix}H_{11}^{k} & \ldots & H_{1M}^{k} \\\vdots & \ldots & \vdots \\H_{N\; 1}^{k} & \ldots & H_{N\; M}^{k}\end{bmatrix}}$represents channel parameters from the M transmitting antennas of thetransmitter to the N receiving antennas of the receiver, s^(k)represents a pilot signal of the k^(th) subcarrier, e^(jθ) ^(l)represents a phase shift on receiving antenna n caused by phase noise,e^(jθm) represents a phase shift on transmitting antenna m caused byphase noise, ICI_(i) represents inter-carrier interference of the l^(th)channel estimation preamble signal, and z_(l) represents a noise of thel^(th) channel estimation preamble signal.

According to LS estimation, the channel estimation parameters {

_(nm) ^(k), ∀n,m} from the transmitting antenna m to the receivingantenna n may be obtained, which are as shown in formula (37).

$\begin{matrix}{{{\hat{H}}_{nm}^{k} = {\frac{y_{n}^{k}(l)}{s^{k}} \approx {H_{nm}^{k}e^{j{({\varphi_{n} + \theta_{m}})}}}}},{{\forall n} = \left\{ {1,\ldots,N} \right\}},{{\forall m} = \left\{ {1,\ldots,M} \right\}},{k \in K}} & (37)\end{matrix}$

In order to represent all of channel estimations of the k^(th)subcarrier, namely {

_(nm) ^(k), ∀n,m}, it is assumed that the m^(th) antenna sends withk_(m) numbers of channel estimation preamble signals and the k^(th)subcarrier is a subcarrier for sending a pilot signal, then a channelestimation of the k^(th) subcarrier may be expressed by formula (38).

$\begin{matrix}{{{\hat{H}}_{n\; m}^{k} \approx {H_{n\; m}^{k}e^{j{({\varphi_{k_{m}} + \theta_{k_{m}}})}}}},{{\forall n} = \left\{ {1,\cdots,N} \right\}},{{\forall m} = \left\{ {1,\cdots,M} \right\}}} & (38)\end{matrix}$

where H_(nm) ^(k) represents an actual channel parameter from thetransmitting antenna m to the receiving antenna n. In this case, theactual channel parameter

^(k) from the M transmitting antennas to the N receiving antennas may beexpressed by formula (39).

$\begin{matrix}{{H^{k =}\begin{bmatrix}H_{11}^{k} & \ldots & {H_{1m}^{k}\mspace{11mu}\ldots} & H_{1M}^{k} \\\vdots & \ldots & {H_{nm}^{k}\mspace{11mu}\ldots} & \vdots \\H_{N\; 1}^{k} & \ldots & {H_{N\; m}^{k}\mspace{11mu}\ldots} & H_{N\; M}^{k}\end{bmatrix}},{{\forall n} = \left\{ {1,\ldots,N} \right\}},{\quad{{{\forall m} = \left\{ {1,\ldots,M} \right\}},{k \in K}}}} & (39)\end{matrix}$

At a data demodulation stage, it is necessary to track a phase shiftcaused by a phase noise and a frequency offset. Specifically, a pilotsignal may be inserted into an OFDM data symbol, and the phase shift isestimated via the pilot signal. Receiving signals on the k^(th) pilotsubcarrier of the l^(th) OFDM data symbol may be expressed by formula(40).

$\begin{matrix}{\begin{bmatrix}{y_{1}^{k}(l)} \\\vdots \\{y_{N}^{k}(l)}\end{bmatrix} = {{\begin{bmatrix}e^{j\;\phi_{1}} & \ldots & 0 \\\vdots & \ldots & \vdots \\0 & \ldots & e^{j\;\phi_{N}}\end{bmatrix}{{H^{k}\begin{bmatrix}e^{j\;\psi_{1}} & \ldots & 0 \\\vdots & \ldots & \vdots \\0 & \ldots & e^{j\;\psi_{M}}\end{bmatrix}}\begin{bmatrix}s_{1}^{k} \\̑ \\s_{m}^{k}\end{bmatrix}}} + {ICI}_{l} + z_{l}}} & (40)\end{matrix}$

where ϕ_(n) represents a phase shift angle caused by the phase noise ofthe receiving antenna n at the data modulation stage, and Ψ_(m)represents a phase shift angle caused by the phase noise of thetransmitting antenna m at the data modulation stage.

The formulas (38) and (39) are substituted into formula (40) to obtainformula (41).

$\begin{matrix}{\begin{bmatrix}{y_{1}^{k}(l)} \\\vdots \\{y_{N}^{k}(l)}\end{bmatrix} \approx {\begin{bmatrix}{\sum\limits_{m = 1}^{M}{{\hat{H}}_{1m}^{k}s_{m}^{k}e^{j\;\xi_{1m}}}} \\\vdots \\{\sum\limits_{m = 1}^{M}{{\hat{H}}_{Nm}^{k}s_{m}^{k}e^{j\;\xi_{Nm}}}}\end{bmatrix} + {ICI}_{l} + z_{l}}} & (41)\end{matrix}$

In the first estimation method in the embodiment of the presentdisclosure, all the pilot subcarriers are utilized for estimation. Inthis case, formula (41) may be modified into a form as shown in formula(42).

$\begin{matrix}{\begin{bmatrix}{y_{1}^{k}(l)} \\\vdots \\{y_{N}^{k}(l)}\end{bmatrix} \approx {\quad{\underset{\underset{H^{k}}{︸}}{\begin{bmatrix}{{\hat{H}}_{11}^{k}s_{1}^{k}} & \ldots & {{\hat{H}}_{1M}^{k}s_{M}^{k}} & 0 & \ldots & 0 & 0 & \ldots & 0 \\0 & \ldots & 0 & {{\hat{H}}_{21}^{k}s_{1}^{k}} & \ldots & {{\hat{H}}_{2M}^{k}s_{1}^{k}} & \vdots & \ldots & \vdots \\\vdots & \ldots & \vdots & \vdots & \vdots & \vdots & 0 & \ldots & 0 \\0 & \ldots & 0 & 0 & \ldots & 0 & {{\hat{H}}_{N\; 1}^{k}s_{1}^{k}} & \ldots & {{\hat{H}}_{NM}^{k}s_{M}^{k}}\end{bmatrix}}{\quad{\underset{\underset{e^{j\;\xi}}{︸}}{\begin{bmatrix}e^{j\;\xi_{11}} \\\vdots \\e^{j\;\xi_{1M}} \\e^{j\;\xi_{21}} \\\vdots \\e^{j\;\xi_{NM}}\end{bmatrix}} + {ICI}_{l} + z_{l}}}}}} & (42)\end{matrix}$

It is assumed that a set of all the pilot subcarriers is p={p₁, . . .,p_(|p|)}, wherein |p| represents a cardinal number of the set P.Receiving data of all the pilot subcarriers are merged to obtain formula(43).

$\begin{matrix}{\underset{\underset{\overset{\_}{y}}{︸}}{\begin{bmatrix}{y_{1}^{p_{1}}(l)} \\\vdots \\{y_{N}^{p_{1}}(l)} \\{y_{1}^{p_{2}}(l)} \\\vdots \\{y_{N}^{p_{p}}(l)}\end{bmatrix}} = {{\underset{\overset{\sim}{H}}{\underset{︸}{\begin{bmatrix}{\overset{\sim}{H}}^{p_{1}} \\\vdots \\{\overset{\sim}{H}}^{p_{p}}\end{bmatrix}}}e^{j\;\xi}} + {ICI}_{l} + z_{l}}} & (43)\end{matrix}$

By utilizing the LS estimation method, a channel phase shift parametere^(jξ) from the M transmitting antennas to the N receiving antennas maybe expressed by formula (44).

$\begin{matrix}{\;{e^{j\;\xi} = {{\left\lbrack {\left\lbrack \overset{\sim}{H} \right\rbrack^{\dagger}\overset{\sim}{H}} \right\rbrack^{-}\;\left\lbrack \overset{\sim}{H} \right\rbrack}^{\dagger}\;\overset{\sim}{y}}}} & (44)\end{matrix}$

Specifically, a complete formula of the formula (44) is as shown byformula (45).

$\begin{matrix}{\begin{bmatrix}e^{j\;\xi_{11}} & \cdots & e^{j\;\xi_{1M}} \\\vdots & \vdots & \vdots \\e^{j\;\xi_{N\; 1}} & \cdots & e^{j\;\xi_{NM}}\end{bmatrix}{\quad{= {{\left\lbrack {\begin{bmatrix}{\overset{\sim}{H}}^{p_{1}} \\\vdots \\{\overset{\sim}{H}}^{p_{p}}\end{bmatrix}^{\dagger}\begin{bmatrix}{\overset{\sim}{H}}^{p_{1}} \\\vdots \\{\overset{\sim}{H}}^{p_{p}}\end{bmatrix}} \right\rbrack^{- 1}\begin{bmatrix}{\overset{\sim}{H}}^{p_{1}} \\\vdots \\{\overset{\sim}{H}}^{p_{p}}\end{bmatrix}}^{\dagger}\begin{bmatrix}{y_{1}^{p_{1}}(l)} \\\vdots \\{y_{N}^{p_{1}}(l)} \\{y_{1}^{p_{2}}(l)} \\\vdots \\{y_{N}^{p_{p}}(l)}\end{bmatrix}}}}} & (45)\end{matrix}$

where y_(n) ^(p)(l) represents a pilot signal arrived at the N receivingantennas which comes from a pilot signal transmitted on a pilotsubcarrier p of the l^(th) data symbol by the M transmitting antennas, prepresents any pilot subcarrier in a pilot subcarrier set {p₁, . . .p_(|p|)} of the l^(th) data symbol, where

^(p) satisfies formula (46).

$\begin{matrix}{{\overset{\sim}{H}}^{p} = {\quad{\quad\left\lbrack \begin{matrix}{{\hat{H}}_{11}^{p}s_{1}^{p}} & \ldots & {{\hat{H}}_{1M}^{p}s_{M}^{p}} & 0 & \ldots & 0 & 0 & \ldots & 0 \\0 & \ldots & 0 & {{\hat{H}}_{21}^{p}s_{1}^{p}} & \ldots & {{\hat{H}}_{2M}^{p}s_{M}^{p}} & \vdots & \ldots & \vdots \\\vdots & \ldots & \vdots & \vdots & \vdots & \vdots & 0 & \ldots & 0 \\0 & \ldots & 0 & 0 & \ldots & 0 & {{\hat{H}}_{N\; 1}^{p}s_{1}^{p}} & \ldots & {{\hat{H}}_{NM}^{p}s_{M}^{p}}\end{matrix} \right\rbrack}}} & (46)\end{matrix}$

In the second estimation method in the embodiment of the presentdisclosure, the channel phase shift parameters of the n^(th) receivingantenna are respectively estimated.

Specifically, ξ₁={ξ₁₁, . . . ,ξ_(1M)}, . . . ,ξ_(N)={ξ_(N1), . . . ,ξ_(NM)} are respectively estimated. Receiving signals of |

| numbers of pilot subcarriers of the n^(th) receiving antenna arecombined, namely

={J₁, . . . ,J_(|)

_(|)}⊆p, and formula (47) is obtained as follows:

$\begin{matrix}{\begin{bmatrix}y_{n}^{J_{1}} \\\vdots \\y_{n}^{J_{J}}\end{bmatrix} \approx {{\underset{{\overset{\ldots}{H}}_{n}}{\underset{︸}{\begin{bmatrix}{{\hat{H}}_{n\; 1}^{J_{1}}s_{1}^{J_{1}}} & \cdots & {{\hat{H}}_{nM}^{J_{1}}s_{M}^{J_{1}}} \\\vdots & \cdots & \vdots \\{{\hat{H}}_{n\; 1}^{J_{J}}s_{1}^{J_{J}}} & \cdots & {{\hat{H}}_{nM}^{J_{J}}s_{M}^{J_{J}}}\end{bmatrix}}}\underset{e^{j\;\xi\; n}}{\underset{︸}{\begin{bmatrix}e^{j\;\xi_{n\; 1}} \\\vdots \\e^{j\;\xi_{nM}}\end{bmatrix}}}} + {ICI}_{l} + z_{l}}} & (47)\end{matrix}$

By utilizing the LS estimation method, a channel phase shift parametere^(jξn) from the M transmitting antennas to the n^(th) receiving antennamay be expressed by formula (48).

$\begin{matrix}{e^{j\;\xi_{n}} = {{\left\lbrack \;{\left\lbrack {\overset{\ldots}{H}}_{n}\; \right\rbrack^{\dagger}{\overset{\ldots}{H}}_{n}}\; \right\rbrack^{- 1}\left\lbrack {\overset{\ldots}{H}}_{n}\; \right\rbrack}^{\dagger}\begin{bmatrix}y_{n}^{J_{1}} \\\vdots \\y_{n}^{J_{J}}\end{bmatrix}}} & (48)\end{matrix}$

Specifically, a complete formula of the formula (48) is as shown byformula (49).

$\begin{matrix}{e^{j\;\xi_{n}} = {\left\lbrack {\begin{bmatrix}{{\hat{H}}_{n\; 1}^{J_{1}}s_{1}^{J_{1}}} & \cdots & {{\hat{H}}_{nM}^{J_{1}}s_{M}^{J_{1}}} \\\vdots & \cdots & \vdots \\{{\hat{H}}_{n\; 1}^{J_{J}}s_{1}^{J_{J}}} & \cdots & {{\hat{H}}_{nM}^{J_{J}}s_{M}^{J_{J}}}\end{bmatrix}^{\dagger}\begin{bmatrix}{{\hat{H}}_{n\; 1}^{J_{1}}s_{1}^{J_{1}}} & \cdots & {{\hat{H}}_{nM}^{J_{1}}s_{M}^{J_{1}}} \\\vdots & \cdots & \vdots \\{{\hat{H}}_{n\; 1}^{J_{J}}s_{1}^{J_{J}}} & \cdots & {{\hat{H}}_{nM}^{J_{J}}s_{M}^{J_{J}}}\end{bmatrix}} \right\rbrack^{- 1}{\quad{\begin{bmatrix}{{\hat{H}}_{n\; 1}^{J_{1}}s_{1}^{J_{1}}} & \cdots & {{\hat{H}}_{nM}^{J_{1}}s_{M}^{J_{1}}} \\\vdots & \cdots & \vdots \\{{\hat{H}}_{n\; 1}^{J_{J}}s_{1}^{J_{J}}} & \cdots & {{\hat{H}}_{nM}^{J_{J}}s_{M}^{J_{J}}}\end{bmatrix}^{\dagger}\begin{bmatrix}{y_{n}^{J_{1}}(l)} \\\vdots \\{y_{n}^{J_{J}}(l)}\end{bmatrix}}}}} & (49)\end{matrix}$

where y_(n) ^(J)(l) represents a pilot signal arrived at the n^(th)receiving antenna in the N receiving antennas which comes from a pilotsignal transmitted on the pilot subcarrier J of the l^(th) data symbolby the M transmitting antennas, J represents any pilot subcarrier in apilot subcarrier set {J₁, . . . J_(|J|)} of the l^(th) data symbol, ands_(m) ^(J) represents a pilot signal transmitted by the m^(th)transmitting antenna in the M transmitting antennas on pilot subcarrierJ of the l^(th) data symbol.

It should be noted that, such method only needs to perform matrixinversion on |

|×|

|. |J|≥M is necessary. Therefore, a range value of |J| is M>|J|>P. Thelarger the |J| is, the more difficult the estimation is, but the higherthe complexity is.

In addition, if the system supports a plurality of different J,different values of e^(jξn) are estimated, and estimation accuracy maybe improved by an averaging method. For example, it is assumed thatthere are T numbers of J in total: J(1), . . . , J(T), e^(jξ) ^(n) ⁽¹⁾,. . .,e^(jξ) _(n) ^((T)) are respectively estimated, and then thechannel phase shift parameter e^(jξ) ^(n) from the M transmittingantennas to the n^(th) receiving antenna may be expressed by formula(50).

$\begin{matrix}{e^{j\;\xi_{n}} = \frac{e^{j\;{\xi_{n}{(1)}}} + \ldots + e^{j\;{\xi_{n}{(T)}}}}{T}} & (50)\end{matrix}$

After the channel phase shift parameter e^(jξ) ^(n) from the m^(th)transmitting antennas to the n^(th) receiving antenna is estimated bythe two above-mentioned methods, a corresponding phase shift angleξ_(nm) may be further obtained through the Euler formula.

After the phase shift caused by the phase noise is tracked, it isnecessary to compensate data. Specifically, at the data demodulationstage, received signals on the d^(th) data subcarrier of the l^(th) OFDMdata symbol may be expressed by formula (51).

$\begin{matrix}{\begin{bmatrix}{y_{1}^{d}(l)} \\\vdots \\{y_{N}^{d}(l)}\end{bmatrix} = {{\underset{\underset{{\hat{H}}_{\xi}^{d}}{︸}}{\begin{bmatrix}{{\hat{H}}_{11}^{d}e^{j\;\xi_{11}}} & \cdots & {{\hat{H}}_{1\; M}^{d}e^{j\;\xi_{1\; M}}} \\\vdots & \vdots & \vdots \\{{\hat{H}}_{N\; 1}^{d}e^{j\;\xi_{N\; 1}}} & \cdots & {{\hat{H}}_{NM}^{d}e^{j\;\xi_{NM}}}\end{bmatrix}}\begin{bmatrix}{x_{1}^{d}(l)} \\\vdots \\{x_{M}^{d}(l)}\end{bmatrix}} + {ICI}_{l} + z_{l}}} & (51)\end{matrix}$

where x_(m) ^(d)(l) represents a QAM signal transmitted by the m^(th)transmitting antenna on the d^(th) subcarrier. The e^(jξ) _(nm) obtainedby calculating according to formula (45), (49) or (50) is substitutedinto formula (51), or after the e^(jξ) ^(nm) is obtained by calculatingaccording to formula (45), (49) or (50), is further obtained accordingto the Euler formula and the ξ_(nm) is then substituted into formula(51). By utilizing the LS estimation method, a signal compensationformula expressed by formula (52) may be obtained.

$\begin{matrix}{\begin{bmatrix}{{\hat{x}}_{1}^{d}(l)} \\\vdots \\{{\hat{x}}_{M}^{d}(l)}\end{bmatrix} = {{\left\lbrack {\left\lbrack H_{\xi}^{d} \right\rbrack^{\dagger}H_{\xi}^{d}} \right\rbrack^{- 1}\left\lbrack H_{\xi}^{d} \right\rbrack}^{\dagger}\begin{bmatrix}{y_{1}^{d}(l)} \\\vdots \\{y_{N}^{d}(l)}\end{bmatrix}}} & (52)\end{matrix}$

where {circumflex over (x)}_(m) ^(d)(l) represents a QAM signaltransmitted by the m^(th) transmitting antenna on the d^(th) subcarrier.

_(ξ) ^(d) is expressed by formula (53).

$\begin{matrix}{H_{\xi}^{d} = \begin{bmatrix}{{\hat{H}}_{11}^{d}e^{j\;\xi_{11}}} & \ldots & {{\hat{H}}_{1\; M}^{d}e^{j\;\xi_{1\; M}}} \\\vdots & \vdots & \vdots \\{{\hat{H}}_{N\; 1}^{d}e^{j\;\xi_{N\; 1}}} & \ldots & {{\hat{H}}_{NM}^{d}e^{j\;\xi_{NM}}}\end{bmatrix}} & (53)\end{matrix}$

where

_(nm) ^(d) in

_(ξ) ^(d) represents a channel estimation parameter from the m^(th)transmitting antenna on the remote transmitter to the n^(th) receivingantenna of the receiver on the d^(th) data subcarrier, and may becalculated by formula (37).

It should be noted that, in formula (36) to formula (53), a serialnumber of a subcarrier is represented sometimes by d and sometimes by k,and all of these are serial numbers of subcarriers; different charactersare adopted merely for distinguishing a data signal from a pilot signal.A pilot signal s^(k) in a pilot subcarrier is known at the receivingend, while a data signal x^(d) in a data subcarrier d is unknown at thereceiving end and is the data that needs to be demodulated.

In addition, in order to reduce inter-carrier interference(Inter-Carrier Interference, ICI), when the transmitting antennas of thetransmitter are sending the channel estimation preamble signals, a voidsubcarrier may be inserted between the pilot signals. In one preferablesolution, a same number of void subcarriers may be inserted between thepilot signals. The larger a quantity of the inserted void subcarriersis, the smaller a value of the ICI is.

In embodiment five of the present disclosure, the method in theembodiment of the present disclosure is further illustrated by taking asystem with 2×2 MIMO-OFDM and K=16 numbers of subcarriers as an example.In this case, M=2, and N=2. In addition, two receiving antennas of thereceiver are incoherent, or two transmitting antennas of the remotetransmitter are incoherent, or two receiving antennas of the receiverand two transmitting antennas of the remote transmitter are bothincoherent.

FIG. 11 is a schematic diagram of another transmission manner of achannel preamble signal in an embodiment of the present disclosure. Inthe embodiment of the present disclosure, a manner for the twotransmitting antennas to transmit channel estimation preamble signals inturns is as shown in FIG. 11. Transmitting antenna 1 transmits the firstchannel estimation preamble signal and does not transmit on the secondchannel estimation preamble signal; transmitting antenna 2 transmits thesecond channel estimation preamble signal and does not transmit on thefirst channel estimation preamble signal, where s^(k)∈{−1,1}, ∀k∈{0, . .. ,15}.

Through formula (37), channel estimations may be obtained as shown informula (54).

$\begin{matrix}{{{{\hat{H}}_{n\; 1}^{k} = {\frac{y_{n}^{k}(1)}{s^{k}} \approx {H_{n\; 1}^{k}e^{j{({\varphi_{n} + \theta_{1}})}}}}},{{\forall n} = \left\{ {1,2} \right\}},{k \in K}}{{{\hat{H}}_{n\; 2}^{k} = {\frac{y_{n}^{k}(2)}{s^{k}} \approx {H_{n\; 2}^{k}e^{j{({\varphi_{n} + \theta_{2}})}}}}},{{\forall n} = \left\{ {1,2} \right\}},{k \in K}}} & (54)\end{matrix}$

where y_(n) ^(k)(l) represents a received signal on the k^(th)subcarrier of the l^(th) channel preamble signal by n^(th) receivingantenna.

At a data transmission stage, the transmitter may insert four pilotsignals into OFDM data symbols, which are located on the 2^(nd), 5^(th),11^(th) and 14^(th) subcarriers, that is p={2,5,11,14} . A specifictransmission is as shown in FIG. 4.

By adopting the first method for phase tracking and estimation, formula(55) may be obtained according to formula (44).

$\begin{matrix}{\begin{bmatrix}e^{j\;\xi_{11}} \\e^{j\;\xi_{12}} \\e^{j\;\xi_{21}} \\e^{j\;\xi_{22}}\end{bmatrix} = {{\left\lbrack {\left\lbrack \overset{\sim}{H} \right\rbrack^{\dagger\;}\overset{\sim}{H}} \right\rbrack^{- 1}\left\lbrack \;\overset{\sim}{H} \right\rbrack}^{\dagger}\begin{bmatrix}y_{1}^{2} \\y_{2}^{2} \\y_{1}^{5} \\y_{2}^{5} \\y_{1}^{11} \\y_{2}^{11} \\y_{1}^{14} \\y_{2}^{14}\end{bmatrix}}} & (55)\end{matrix}$

Please refer to the expressions in formula (43) and formula (42) for thespecific meaning of

, which will not be described in detain redundantly herein.

After the channel phase shift parameters e^(jξ) ¹¹ , e^(jξ) ¹² , e^(jξ)²¹ , e^(jξ) ²² between the two transmitters and the two receivers ofcorresponding data symbols are obtained according to formula (55),channel phase shift angles {ξ₁₁, ξ₁₂, ξ₂₁, ξ₂₂} may be further obtained.

Finally, at a data demodulation stage, the receiver performs signalcompensation on received data signals. Formula (56) is obtainedaccording to the formula (52).

$\begin{matrix}{\begin{bmatrix}{\hat{x}}_{1}^{d} \\{\hat{x}}_{2}^{d}\end{bmatrix} = {{\left\lbrack {\left\lbrack H_{\xi}^{d} \right\rbrack^{\dagger}H_{\xi}^{d}} \right\rbrack^{- 1}\left\lbrack H_{\xi}^{d} \right\rbrack}^{\dagger}\begin{bmatrix}{y_{1}^{d}(l)} \\{y_{2}^{d}(l)}\end{bmatrix}}} & (56)\end{matrix}$

where {circumflex over (x)}₁ ^(d) and {circumflex over (x)}₂ ^(d)respectively represent QAM signals sent on the d^(th) data subcarrier ofthe l^(th) data symbol by the transmitting antenna 1 and thetransmitting antenna 2. y₁ ^(d)(l) and y₂ ^(d)(l) respectively representQAM signals received on the d^(th) data subcarrier of the l^(th) datasymbol by the receiving antenna 1 and the receiving antenna 2. Inaddition, it can be seen from the formula (53) that, a value of

_(ξ) ^(d) may be calculated through the channel estimation parameters informula (54) and the channel phase shift parameters in formula (55),which will not be described redundantly herein in the embodiment of thepresent disclosure.

In the embodiment of the present disclosure, the channel estimationparameters are determined according to the pilot signals in the channelestimation preamble channel, and the channel phase shift parameters aredetermined according to all the pilot signals sent on a data symbol,thereby determining the signal compensation of the data signals on thedata symbol according to the channel estimation parameters and thechannel phase shift parameters.

In embodiment six of the present disclosure, the method in theembodiment of the present disclosure is further illustrated by taking aMIMO-OFDM WiFi system with 2×2 and K=64 numbers of subcarriers as anexample. In this case, M=2, and N=2. In addition, two receiving antennasof the receiver are incoherent, or two transmitting antennas of theremote transmitter are incoherent, or two receiving antennas of thereceiver and two transmitting antennas of the remote transmitter areboth incoherent.

In the 2×2 MIMO-OFDM WiFi system, there are K=64 subcarriers in total.There are only 52 useful subcarriers in 64 subcarriers, wherein the0^(th) to the 5^(th) subcarriers and the 59^(th) to the 63^(rd)subcarriers are void subcarriers all the time and do not transmit anyinformation, and the 32^(nd) subcarrier is a direct current subcarrierand does not transmit any information. Please refer to FIG. 5 fordetails.

In the embodiment of the present disclosure, a manner for the twotransmitting antennas to transmit the channel estimation preamblesignals in turns may be as shown in FIG. 11. Transmitting antenna 1transmits the first channel estimation preamble signal and does nottransmit on the second channel estimation preamble signal; andtransmitting antenna 2 transmits the second channel estimation preamblesignal and does not transmit on the first channel estimation preamblesignal, where s^(k)ξ{−1,1}, ∀k∈{0, . . . , 15}.

Through formula (37), channel estimations may be obtained as shown informula (57).

$\begin{matrix}{{{{\hat{H}}_{n\; 1}^{k} = {\frac{y_{n}^{k}(1)}{s^{k}} \approx {H_{n\; 1}^{k}e^{j{({\varphi_{n} + \theta_{1}})}}}}},{{\forall n} = \left\{ {1,2} \right\}},{k \in K}}{{{\hat{H}}_{n\; 2}^{k} = {\frac{y_{n}^{k}(2)}{s^{k}} \approx {H_{n\; 2}^{k}e^{j{({\varphi_{n} + \theta_{2}})}}}}},{{\forall n} = \left\{ {1,2} \right\}},{k \in K}}} & (57)\end{matrix}$

where y_(n) ^(k)(l) represents a received signal on the k^(th)subcarrier of the l^(th) channel preamble signal by n^(th) receivingantenna.

At a data transmission stage, the transmitter may insert 8 pilot signalsinto OFDM data symbols, which are located on the 10^(th), 13^(th),22^(nd), 25^(th), 39^(th), 42^(nd), 51^(st) and 54^(th) subcarriers,that is, p={10,13,22,25,39,42,51,54}.

The second method for phase tracking and estimation is adopted. It isassumed that there are T=4 numbers of J in total: J(1)={10,54},J(2)={13,51}, J(3)={22,42}, J(4)={25,39}. The system may select anypilot subcarrier set among J(1), J(2), J(3), J(4) to determine thechannel phase shift parameters. Of course, the system may also selectother pilot subcarrier set to determine the channel phase shiftparameters, such as, for example, J(5)={22,42,39} and the like, as longas a cardinal number |J(i)| of a pilot subcarrier set J(i) is largerthan or equal to the number (i.e., 2) of the transmitting antennas andis smaller than or equal to the number (i.e., 8) of all the pilotsubcarriers. In the embodiment of the present disclosure, one pilotsubcarrier set J(i) may be selected to estimate e^(jξ) ^(n) ^((i))according to formula (48); or, a plurality of pilot subcarrier sets J(i)may be selected to estimate a plurality of e^(jξ) ^(n) ^((i)) accordingto formula (48), and e^(jξ) ^(n) is then obtained according to formula(50).

In the embodiment of the present disclosure, as an example, the channelphase shift parameters are estimated with T={J(1), J(2), J(3), J(4)}.

According to formula (48), e^(jξ) ^(n) ⁽¹⁾, . . . , e^(jξ) ^(n) ^((T))are respectively estimated. According to formula (50), e^(jξ) ^(n) isthen obtained, which is further used to obtain {ξ₁₁, ξ₁₂, ξ₂₁, ξ₂₂}.

Finally, at a data demodulation stage, the receiver performs signalcompensation on the received data signals. Formula (58) is obtainedaccording to formula (52).

$\begin{matrix}{\begin{bmatrix}{\hat{x}}_{1}^{d} \\{\hat{x}}_{2}^{d}\end{bmatrix} = {{\left\lbrack {\left\lbrack H_{\xi}^{d} \right\rbrack^{\dagger}H_{\xi}^{d}} \right\rbrack^{- 1}\left\lbrack H_{\xi}^{d} \right\rbrack}^{\dagger}\begin{bmatrix}{y_{1}^{d}(l)} \\{y_{2}^{d}(l)}\end{bmatrix}}} & (58)\end{matrix}$

where {circumflex over (x)}₁ ^(d) and {circumflex over (x)}₂ ^(d)respectively represent QAM signals sent on the d^(th) data subcarrier ofthe l^(th) data symbol by the transmitting antenna 1 and thetransmitting antenna 2. y₁ ^(d)(l) and y₂ ^(d)(l) respectively representQAM signals received on the d^(th) data subcarrier of the l^(th) datasymbol by the receiving antenna 1 and the receiving antenna 2. Inaddition, it can be seen from the formula (53) that, a value of

_(ξ) ^(d) may be calculated through the channel estimation parameters informula (54) and the channel phase shift parameters in formula (55).which will not be described redundantly herein in the embodiment of thepresent disclosure.

In the embodiment of the present disclosure, the channel estimationparameters are determined according to the pilot signals in the channelestimation preamble channel, and the channel phase shift parameters aredetermined according to all the pilot signals sent on a data symbol,thereby determining the signal compensation of the data signals on thedata symbol according to the channel estimation parameters and thechannel phase shift parameters.

In addition, although only the QAM signal is adopted at the data sendingstage in embodiments one to six of the present disclosure, embodimentsone to six of the present disclosure are actually not limited to use theQAM signal and may adopt other categories of data signal, such as, forexample, a binary phase shift keying (BPSK) signal, a quadrature phaseshift keying (QPSK) signal, etc.

FIG. 12 is a flowchart of a method for sending a signal in an embodimentof the present disclosure. The method in FIG. 12 is executed by atransmitter.

1201, the transmitter sends, via M transmitting antennas, a plurality ofchannel estimation preamble signals to N receiving antennas of a remotereceiver.

The plurality of channel estimation preamble signals contain first pilotsignals of the M transmitting antennas, where M and N are integerslarger than 1. The first pilot signals in the plurality of channelestimation preamble signals are used by the remote receiver fordetermining channel estimation parameters from the M transmittingantennas to the N receiving antennas, and each one of the plurality ofchannel estimation preamble signals is separately transmitted by onetransmitting antenna in the M transmitting antennas.

1202, the transmitter sends, via the M transmitting antennas, datasignals and second pilot signals on a data symbol.

The second pilot signals are used by the remote receiver for determiningchannel phase shift parameters from the M transmitting antennas to the Nreceiving antennas, and further determining signal compensation of thedata signals according to the channel estimation parameters and thechannel phase shift parameters.

In the embodiment of the present disclosure, the transmitter sends, viamultiple paths of transmitting antennas, the channel estimation preamblesignals to multiple antennas of the receiver and sends the data signalsand the pilot signals on the data symbol, such that the receiver is ableto determine the channel estimation parameters and the channel phaseshift parameters between the transmitting antennas and the receivingantennas according to the pilot signals in the channel estimationpreamble signals and the pilot signals on the data symbol, and furtherdetermine the signal compensation of the data signals on the datasymbol.

Optionally, any two adjacent measurement signals of one of the pluralityof channel estimation preamble signals are isolated by at least one voidsubcarrier.

Optionally, one or more subcarriers on the data symbol are used forsending the second pilot signals.

Optionally, the M transmitting antennas of the transmitter are coherentor incoherent.

In addition, the method in the embodiment of the present disclosure mayalso be applied to the transmitter in embodiments one to six of thepresent disclosure, which will not be described redundantly herein inthe embodiment of the present disclosure.

FIG. 13 is a schematic diagram of a structure of a receiver 1300 in anembodiment of the present disclosure. The receiver 1300 may include Nreceiving antennas 1301 and a determining unit 1302.

The N receiving antennas 1301 are configured to receive a plurality ofchannel estimation preamble signals sent by M transmitting antennas of aremote transmitter.

The plurality of channel estimation preamble signals contain first pilotsignals of the M transmitting antennas, where M and N are integerslarger than 1.

The determining unit 1302 is configured to determine channel estimationparameters from the M transmitting antennas to the N receiving antennasaccording to the first pilot signals of the M transmitting antennascontained in the plurality of channel estimation preamble signals.

The N receiving antennas 1301 are further configured to receive datasignals and second pilot signals sent on a first data symbol by the Mtransmitting antennas.

The determining unit 1302 is further configured to determine channelphase shift parameters from the M transmitting antennas to the Nreceiving antennas 1301 according to signals arrived at the N receivingantennas 1301 which come from the second pilot signals sent on the firstdata symbol by the M transmitting antennas.

The determining unit 1302 is further configured to determine, accordingto the channel estimation parameters from the M transmitting antennas tothe N receiving antennas 1301 and the channel phase shift parametersfrom the M transmitting antennas to the N receiving antennas 1301,signal compensation for the data signals arrived at the N receivingantennas 1301 that are sent on the first data symbol by the Mtransmitting antennas.

In the embodiment of the present disclosure, the receiver 1300determines the signal compensation of the data signals according to thechannel estimation parameters from the transmitting antennas of theremote transmitter to the receiving antennas of the receiver and thechannel phase shift parameters of the transmitting antennas of theremote transmitter on the first data symbol, which can improvedemodulation accuracy of transmitted data to a certain extent.

Optionally, a subcarrier set for sending a first pilot signal of them^(th) transmitting antenna in the M transmitting antennas is equal to aset of subcarriers of the m^(th) transmitting antenna, where ∀m={1, . .. ,M}.

Optionally, as one embodiment, the N receiving antennas are coherent,and the M transmitting antennas are coherent.

Optionally, in an embodiment where both the receiver and the transmitterare coherent, in a process of determining the channel phase shiftparameters from the M transmitting antennas to the N receiving antennas1301 according to signals arrived at the N receiving antennas 1301 whichcome from the second pilot signals sent on the first data symbol by theM transmitting antennas, the determining unit 1302 is specificallyconfigured to determine first channel phase shift parameters accordingto a signal arrived at the N receiving antennas 1301 which comes from asecond pilot signal sent on the first data symbol by the mthtransmitting antenna in the M transmitting antennas, wherein the firstchannel phase shift parameters are channel phase shift parameters fromthe m^(th) transmitting antenna in the M transmitting antennas to the Nreceiving antennas 1301, where ∀m={1, . . . ,M}.

Further, in a process of determining, according to the signal arrived atthe N receiving antennas 1301 which comes from the second pilot signalsent on the first data symbol by the mth transmitting antenna in the Mtransmitting antennas, channel phase shift parameters from the m^(th)transmitting antenna in the M transmitting antennas to the N receivingantennas 1301, the determining unit 1302 is specifically configured to:if there is more than one subcarrier on the first data symbol forsending the second pilot signal, determine, according to the signalarrived at the N receiving antennas 1301 which comes from the secondpilot signal sent on the first data symbol by the m^(th) transmittingantenna in the M transmitting antennas, multiple groups of channel phaseshift parameters from the m^(th) transmitting antenna in the Mtransmitting antennas to the N receiving antennas 1301, and determineaverage values of the multiple groups of channel phase shift parametersas the channel phase shift parameters from the m^(th) transmittingantenna in the M transmitting antennas to the N receiving antennas 1301.

In this case, please refer to formula (24) to formula (26) for themethod for the determining unit 1302 to determine the channel estimationparameters and the channel phase shift parameters, as well asdetermining the signal compensation according to the channel estimationparameters and the channel phase shift parameters, which will not berepeated redundantly herein in the embodiment of the present disclosure.

Optionally, as another embodiment, the N receiving antennas 1301 areincoherent, and/or the M transmitting antennas are incoherent.

Optionally, in an embodiment where the receiver and/or the transmitteris incoherent, in a process of determining the channel phase shiftparameters from the M transmitting antennas to the N receiving antennas1301 according to the pilot signals arrived at the N receiving antennas1301 which come from the second pilot signals sent on the first datasymbol by the M transmitting antennas, the determining unit 1302 isspecifically configured to determine the channel phase shift parametersfrom the M transmitting antennas to the N receiving antennas 1301according to all of pilot signals arrived at the N receiving antennas1301 which come from the second pilot signals sent on the first datasymbol by the M transmitting antennas, where a quantity of pilotsubcarriers where all of the pilot signals are located is not smallerthan M.

In this case, please refer to formula (27) to formula (31) for themethod for the determining unit 1302 to determine the channel estimationparameters and the channel phase shift parameters, as well asdetermining the signal compensation according to the channel estimationparameters and the channel phase shift parameters, which will not berepeated redundantly herein in the embodiment of the present disclosure.

Optionally, in an embodiment where the receiver and/or the transmitteris incoherent, in a process of determining the channel phase shiftparameters from the M transmitting antennas to the N receiving antennas1301 according to pilot signals arrived at the N receiving antennas 1301which come from the second pilot signals sent on the first data symbolby the M transmitting antennas, the determining unit 1302 isspecifically configured to determine, according to at least one group ofpilot signals arrived at the n^(th) receiving antenna in the N receivingantennas 1301 which come from the second pilot signals sent on the firstdata symbol by the M transmitting antennas, the channel phase shiftparameters from the M transmitting antennas to the n^(th) receivingantenna in the N receiving antennas 1301, wherein each one of the atleast one group of pilot signals contains pilot signals received on Jnumbers of subcarriers by the N receiving antennas 1301, and a value ofJ is not smaller than M.

In this case, please refer to formula (32) to formula (35) for themethod for the determining unit 1302 to determine the channel estimationparameters and the channel phase shift parameters, as well asdetermining the signal compensation according to the channel estimationparameters and the channel phase shift parameters, which will not berepeated redundantly herein in the embodiment of the present disclosure.

Further, in a process of determining, according to at least one group ofpilot signals arrived at the n^(th) receiving antenna in the N receivingantennas 1301 which come from the second pilot signals sent on the firstdata symbol by the M transmitting antennas, the channel phase shiftparameters from the M transmitting antennas to the n^(th) receivingantenna in the N receiving antennas 1301, the determining unit 1302 isspecifically configured to determine multiple groups of channel phaseshift parameters from the M transmitting antennas to the n^(th)receiving antenna in the N receiving antennas 1301 according to multiplegroups of pilot signals arrived at the n^(th) receiving antenna in the Nreceiving antennas 1301 which come from the second pilot signals sent onthe first data symbol by the M transmitting antennas, and determineaverage values of channel phase shift parameters in the multiple groupsof channel phase shift parameters, that are corresponding to a channelphase shift parameter from the m^(th) transmitting antenna in the Mtransmitting antennas to the n^(th) receiving antenna in the N receivingantennas 1301, as the channel phase shift parameters from the m^(th)transmitting antenna in the M transmitting antennas to the n^(th)receiving antenna in the N receiving antennas 1301.

Optionally, any two adjacent measurement signals of one of the pluralityof channel estimation preamble signals are isolated by at least one voidsubcarrier.

In addition, the receiver 1300 may further execute the method in FIG.10, and has the functions of the receiver in the embodiment as shown inFIG. 10 and in the embodiments one to six, which will not be repeatedredundantly herein in the embodiment of the present disclosure.

FIG. 14 is a schematic diagram of a structure of a transmitter 1400 inan embodiment of the present disclosure. The transmitter 1400 mayinclude a signal generating unit 1401 and M transmitting antennas 1402.

The signal generating unit 1401 is configured to generate a plurality ofchannel estimation preamble signals.

The plurality of channel estimation preamble signals contain first pilotsignals of the M transmitting antennas 1402, where M and N are integerslarger than 1. The first pilot signals in the plurality of channelestimation preamble signals are used by a remote receiver fordetermining channel estimation parameters from the M transmittingantennas 1402 to the N receiving antennas.

The M transmitting antennas 1402 are configured to send the plurality ofchannel estimation preamble signals to N receiving antennas of theremote receiver.

Each one of the plurality of channel estimation preamble signals isseparately transmitted by one transmitting antenna in the M transmittingantennas 1402.

The signal generating unit 1401 is further configured to generate datasignals and second pilot signals.

The M transmitting antennas 1402 are further configured to send the datasignals and the second pilot signals on a data symbol.

The second pilot signals are used by the remote receiver for determiningchannel phase shift parameters from the M transmitting antennas 1402 tothe N receiving antennas, and further determining signal compensation ofthe data signals according to the channel estimation parameters and thechannel phase shift parameters.

In the embodiment of the present disclosure, the transmitter 1400 sendsthe channel estimation preamble signals to multiple receiving antennasvia multiple transmitting antennas and sends the data signals and thepilot signals on the data symbol, such that the receiver is able todetermine the channel estimation parameters and the channel phase shiftparameters from the transmitting antennas to the receiving antennasaccording to the pilot signals in the channel estimation preamblesignals and the pilot signals on the data symbol, and further todetermine the signal compensation of the data signals on the datasymbol.

Optionally, any two adjacent measurement signals of one of the pluralityof channel estimation preamble signals are isolated by at least one voidsubcarrier.

Optionally, there is one or more subcarriers on the data symbol forsending the second pilot signals.

Optionally, the M transmitting antennas of the transmitter are coherentor incoherent.

In addition, the transmitter 1400 may further execute the method in FIG.12, and has the functions of the transmitter 1400 in the embodiment inFIG. 12 and in the embodiments one to six, which will not be repeatedredundantly herein in the embodiment of the present disclosure.

FIG. 15 is a schematic diagram of a structure of a receiver 1500 in anembodiment of the present disclosure. The receiver 1500 may include aprocessor 1502, a memory 1503 and N receiving antennas 1501.

The processor 1502 may receive, via the N receiving antennas 1501, aplurality of channel estimation preamble signals sent by M transmittingantennas of a remote transmitter .

The plurality of channel estimation preamble signals contain first pilotsignals of the M transmitting antennas, where M and N are integerslarger than 1.

The processor 1502 may further determine channel estimation parametersfrom the M transmitting antennas to the N receiving antennas 1501according to the first pilot signals of the M transmitting antennascontained in the plurality of channel estimation preamble signals.

The processor 1502 may further receive data signals and second pilotsignals sent on a first data symbol by the M transmitting antennas 1501.

The processor 1502 may further determine channel phase shift parametersfrom the M transmitting antennas to the N receiving antennas 1501according to signals arrived at the N receiving antennas 1501 which comefrom the second pilot signals sent on the first data symbol by the Mtransmitting antennas.

The processor 1502 may further determine, according to the channelestimation parameters from the M transmitting antennas to the Nreceiving antennas 1501 and the channel phase shift parameters from theM transmitting antennas to the N receiving antennas 1501, signalcompensation for the data signals arrived at the N receiving antennas1501 which are sent on the first data symbol by the M transmittingantennas.

The memory 1503 may store an instruction for making the processor 1502to execute the above-mentioned operations.

The processor 1502 controls an operation of the receiver 1500, and theprocessor 1502 may also be referred to as a CPU (central processingunit). The memory 1503 may include a read-only memory and a randomaccess memory and provide instructions and data to the processor 1502. Apart of the memory 1503 may further include a nonvolatile random accessmemory (NVRAM). Components of the receiver 1500 are coupled together bya bus system 1506, where besides a data bus, the bus system 1506 mayfurther include a power source bus, a control bus and a status signalbus or the like. But for clarity, the various buses in the figure aremarked as the bus system 1506.

The method disclosed in the above-mentioned embodiment of the presentdisclosure may be applied to the processor 1502 or may be implemented bythe processor 1502. The processor 1502 may be an integrated circuit chipwith a signal processing capability. In an implementation process, thesteps of the above-mentioned method may be completed by an integratedlogic circuit of hardware or a software instruction in the processor1502. The above-mentioned processor 1502 may be a general-purposeprocessor, a digital signal processor (DSP), an application-specificintegrated circuit (ASIC), a field-programmable gate array (FPGA) orother programmable logic device, a discrete gate or a transistor logicdevice, and a discrete hardware component, and may implement or executethe methods, the steps and the logic block diagrams disclosed in theembodiment of the present disclosure. The general-purpose processor maybe a microprocessor, or the processor may be any conventional processoror the like. The steps of the method disclosed in the embodiment of thepresent disclosure may be directly executed and completed by a hardwaredecoding processor, or is executed and completed by a combination ofhardware and software modules in the decoding processor. The softwaremodule may be located in a mature storage medium in the art, such as arandom access memory, a flash memory, a read-only memory, a programmableread-only memory or an electrically erasable programmable memory, aregister, etc. The storage medium is located in the memory 1503, and theprocessor 1502 reads information in the memory 1503 and completes thesteps of the above-mentioned method in combination with the hardwarethereof.

In the embodiment of the present disclosure, the receiver 1500determines the signal compensation of the data signals according to thechannel estimation parameters from the transmitting antennas of theremote transmitter to the receiving antennas of the receiver and thechannel phase shift parameters of the transmitting antennas of theremote transmitter on a first data symbol, which can improvedemodulation accuracy of data transmission to a certain extent.

Optionally, a subcarrier set for sending a first pilot signal of them^(th) transmitting antenna in the M transmitting antennas is equal to aset of subcarriers of the m^(th) transmitting antenna, where ∀m={1, . .. ,M}.

Optionally, as one embodiment, the N receiving antennas are coherent,and the M transmitting antennas are coherent.

Optionally, in an embodiment where both the receiver and the transmitterare coherent, in a process of determining channel phase shift parametersfrom the M transmitting antennas to the N receiving antennas 1501according to signals arrived at the N receiving antennas 1501 which comefrom the second pilot signals sent on the first data symbol by the Mtransmitting antennas, the processor 1502 is specifically configured todetermine first channel phase shift parameters according to a signalarrived at the N receiving antennas 1501 which comes from a second pilotsignal sent on the first data symbol by the mth transmitting antenna inthe M transmitting antennas, wherein the first channel phase shiftparameters are channel phase shift parameters from the m^(th)transmitting antenna in the M transmitting antennas to the N receivingantennas 1501, where ∀m={1, . . . ,M}.

Further, in a process of determining, according to the signal arrived atthe N receiving antennas 1501 which comes from the second pilot signalsent on the first data symbol by the mth transmitting antenna in the Mtransmitting antennas, channel phase shift parameters from the m^(th)transmitting antenna in the M transmitting antennas to the N receivingantennas 1501, the processor 1502 is specifically configured to: ifthere is more than one subcarrier on the first data symbol for sendingthe second pilot signal, determine, according to signals arrived at theN receiving antennas 1501 which come from the second pilot signals senton a plurality of subcarriers of the first data symbol by the m^(th)transmitting antenna in the M transmitting antennas, multiple groups ofchannel phase shift parameters from the m^(th) transmitting antenna inthe M transmitting antennas to the N receiving antennas 1501, anddetermine average values of the multiple groups of channel phase shiftparameters as the channel phase shift parameters from the m^(th)transmitting antenna in the M transmitting antennas to the N receivingantennas 1501.

In this case, please refer to formula (24) to formula (26) for themethod for the processor 1302 to determine the channel estimationparameters and the channel phase shift parameters, as well asdetermining the signal compensation according to the channel estimationparameters and the channel phase shift parameters, which will not berepeated redundantly herein in the embodiment of the present disclosure.

Optionally, as another embodiment, the N receiving antennas 1501 areincoherent, and/or the M transmitting antennas are incoherent.

Optionally, in an embodiment where the receiver and/or the transmitteris incoherent, in a process of determining the channel phase shiftparameters from the M transmitting antennas to the N receiving antennas1501 according to the pilot signals arrived at the N receiving antennas1501 which come from the second pilot signals sent on the first datasymbol by the M transmitting antennas, the processor 1502 isspecifically configured to determine the channel phase shift parametersfrom the M transmitting antennas to the N receiving antennas 1501according to all of pilot signals arrived at the N receiving antennas1501 which come from the second pilot signals sent on the first datasymbol by the M transmitting antennas, where a quantity of pilotsubcarriers where all the pilot signals are located is not smaller thanM.

In this case, please refer to formula (27) to formula (31) for themethod for the processor 1502 to determine the channel estimationparameters and the channel phase shift parameters, as well asdetermining the signal compensation according to the channel estimationparameters and the channel phase shift parameters, which will not berepeated redundantly herein in the embodiment of the present disclosure.

Optionally, in an embodiment where the receiver and/or the transmitteris incoherent, in a process of determining the channel phase shiftparameters from the M transmitting antennas to the N receiving antennas1501 according to pilot signals arrived at the N receiving antennas 1501which come from the second pilot signals sent on the first data symbolby the M transmitting antennas, the processor 1502 is specificallyconfigured to determine, according to at least one group of pilotsignals arrived at the n^(th) receiving antenna in the N receivingantennas 1501 which come from the second pilot signals sent on the firstdata symbol by the M transmitting antennas, the channel phase shiftparameters from the M transmitting antennas to the n^(th) receivingantenna in the N receiving antennas 1501, wherein each one of the atleast one group of pilot signals contains pilot signals received on Jnumbers of subcarriers by the N receiving antennas 1501, and a value ofJ is not smaller than M.

In this case, please refer to formula (32) to formula (35) for themethod for the processor 1502 to determine the channel estimationparameters and the channel phase shift parameters, as well asdetermining the signal compensation according to the channel estimationparameters and the channel phase shift parameters, which will not berepeated redundantly herein in the embodiment of the present disclosure.

Further, in a process of determining, according to at least one group ofpilot signals arrived at the n^(th) receiving antenna in the N receivingantennas 1301 which come from the second pilot signals sent on the firstdata symbol by the M transmitting antennas, the channel phase shiftparameters from the M transmitting antennas to the n^(th) receivingantenna in the N receiving antennas 1501, the processor 1502 isspecifically configured to determine multiple groups of channel phaseshift parameters from the M transmitting antennas to the n^(th)receiving antenna in the N receiving antennas 1501 according to multiplegroups of pilot signals arrived at the n^(th) receiving antenna in the Nreceiving antennas 1501 which come from the second pilot signals sent onthe first data symbol by the M transmitting antennas, and determineaverage values of channel phase shift parameters in the multiple groupsof channel phase shift parameters, that are corresponding to a channelphase shift parameter from the n^(th) transmitting antenna in the Mtransmitting antennas to the n^(th) receiving antenna in the N receivingantennas 1501, as the channel phase shift parameters from the m^(th)transmitting antenna in the M transmitting antennas to the n^(th)receiving antenna in the N receiving antennas 1501.

Optionally, any two adjacent measurement signals of one of the pluralityof channel estimation preamble signals are isolated by at least one voidsubcarrier.

In addition, the receiver 1500 may further execute the method in FIG.10, and has the functions of the receiver in the embodiment as shown inFIG. 10 and in the embodiments one to six, which will not be repeatedredundantly herein in the embodiment of the present disclosure.

FIG. 16 is a schematic diagram of a structure of a transmitter 1600 inan embodiment of the present disclosure. The transmitter 1600 mayinclude a processor 1602, M transmitting antennas 1601 and a memory1603.

The processor 1602 may be configured to generate a plurality of channelestimation preamble signals, and send, via the M transmitting antennas1601, the plurality of channel estimation preamble signals to Nreceiving antennas of a remote receiver.

The plurality of channel estimation preamble signals contain first pilotsignals of the M transmitting antennas 1601, where M and N are integerslarger than 1. The first pilot signals in the plurality of channelestimation preamble signals are used by a remote receiver fordetermining channel estimation parameters from the M transmittingantennas 1601 to the N receiving antennas, and each of the plurality ofchannel estimation preamble signals is separately transmitted by onetransmitting antenna of the M transmitting antennas 1601.

The processor 1602 may be further configured to generate data signalsand second pilot signals, and send the data signals and the second pilotsignals on a data symbol via the M transmitting antennas 1601.

The second pilot signals are used by the remote receiver for determiningchannel phase shift parameters from the M transmitting antennas 1601 tothe N receiving antennas, and further determining signal compensation ofthe data signals according to the channel estimation parameters and thechannel phase shift parameters.

The memory 1603 may store an instruction for making the processor 1602to execute the above-mentioned operations.

The processor 1602 controls an operation of the transmitter 1600, andthe processor 1602 can also be referred to as a CPU (Central ProcessingUnit).The memory 1603 may include a read-only memory and a random accessmemory, and provide instructions and data to the processor 1602. A partof the memory 1603 may further include a nonvolatile random accessmemory (NVRAM). Components of the transmitter 1600 are coupled togetherby a bus system 1606, wherein besides a data bus, the bus system 1606may further include a power source bus, a control bus and a statussignal bus or the like. But for clarity, the various buses in the figureare marked as the bus system 1606.

The method disclosed in the above-mentioned embodiment of the presentdisclosure may he applied to the processor 1602 or may be implemented bythe processor 1602. The processor 1602 may be an integrated circuit chipwith a signal processing capacity. In an implementation process, thesteps of the above-mentioned method may be completed by an integratedlogic circuit of hardware or a software instruction in the processor1602. The above-mentioned processor 1602 may be a general-purposeprocessor, a digital signal processor (DSP), an application-specificintegrated circuit (ASIC), a field-programmable gate array (FPGA) orother programmable logic device, a discrete gate or a transistor logicdevice, and a discrete hardware component, and may implement or executethe methods, the steps and the logic block diagrams disclosed in theembodiment of the present disclosure. The general-purpose processor maybe a microprocessor, or the processor may be any conventional processoror the like. The steps of the method disclosed in the embodiment of thepresent disclosure may be directly executed and completed by a hardwaredecoding processor, or is executed and completed by a combination ofhardware and software modules in the decoding processor. The softwaremodule may be located in a mature storage medium in the art, such as arandom access memory, a flash memory, a read-only memory, a programmableread-only memory or an electrically erasable programmable memory, aregister, etc. The storage medium is located in the memory 1603, and theprocessor 1602 reads information in the memory 1603 and completes thesteps of the above-mentioned method in combination with the hardwarethereof.

In the embodiment of the present disclosure, the transmitter 1600 sendsthe channel estimation preamble signals to multiple receiving antennasvia multiple transmitting antennas and sends the data signals and thepilot signals on the data symbol, such that the receiver is able todetermine the channel estimation parameters and the channel phase shiftparameters from the transmitting antennas to the receiving antennasaccording to the pilot signals in the channel estimation preamblesignals and the pilot signals on the data symbol, and further todetermine the signal compensation of the data signals on the datasymbol.

Optionally, any two adjacent measurement signals of one of the pluralityof channel estimation preamble signals are isolated by at least one voidsubcarrier.

Optionally, there is one or more subcarriers on the data symbol forsending the second pilot signals.

Optionally, the M transmitting antennas of the transmitter are coherentor incoherent.

In addition, the transmitter 1600 may further execute the method in FIG.12, and has the functions of the transmitter 1600 in the embodiment inFIG. 12 and in the embodiments one to six, which will not be repeatedredundantly herein in the embodiment of the present disclosure.

FIG. 17 is a schematic diagram of a structure of an MIMO-OFDM system1700 in an embodiment of the present disclosure. The MIMO-OFDM system1700 may include a transmitter 1701 and a receiver 1702.

The receiver 1702 may he the receiver 1300 in the embodiment shown inFIG. 13 or the receiver 1500 in the embodiment shown in FIG. 15, and mayimplement the functions of the receiver in embodiments one to six of thepresent disclosure. The transmitter 1701 may be the transmitter 1400 inthe embodiment shown in FIG. 14 or the transmitter 1600 in theembodiment shown in FIG. 16, and may implement the functions of thetransmitter in the embodiments one to six of the present disclosure,which will not be repeated redundantly herein.

In the embodiment of the present disclosure, the MIMO-OFDM system 1700determines the channel estimation parameters and the channel phase shiftparameters according to the pilot signals of the remote transmitter, andfurther to determine the signal compensation of the receiving end,thereby improving accuracy of an estimated value of transmitted data.

Those of ordinary skill in the art may be aware that, units andalgorithm steps of the examples described in the embodiments disclosedin the present disclosure may be implemented by electronic hardware or acombination of computer software and the electronic hardware. Whetherthese functions are implemented in the form of hardware or software isdetermined by specific applications and design constraint conditions ofthe technical solutions. Those skilled may implement the describedfunctions by using different methods for every specific application, butthis implementation should not be considered to be beyond the scope ofthe present disclosure.

Those skilled in the art to which the present disclosure pertains mayclearly understand that, for convenience and simplicity of description,corresponding processes in the foregoing method embodiments may bereferred to for specific working processes of the system, the apparatusand the units described above, which will not be repeated redundantlyherein.

In several embodiments provided in the present application, it should beunderstood that, the disclosed system, apparatus and method may beimplemented in other manner. For example, the apparatus embodimentsdescribed above are merely exemplary, e.g., partition of the units isonly a logic functionality partition, and other partitioning manners maybe used in a practical implementation. For example, a plurality of unitsor components may be combined or integrated into another system, or somefeatures may be omitted or not implemented. From another point of view,the displayed or discussed mutual coupling or direct coupling orcommunication connection may be indirect coupling or communicationconnection of apparatuses or units through some interfaces, and may bein electrical, mechanical or other form.

The units described as separate components may be separated physicallyor not, the components displayed as units may he physical units or not,namely, may he located in one place, or may be distributed in aplurality of network units. A part of, or all of, the units may beselected to implement the purpose of the technical solutions in theembodiments according to actual needs.

In addition, the functional units in the embodiments of the presentdisclosure may be integrated in a processing unit, or the unitsseparately exist physically, or two or more units are integrated in oneunit.

If the function is implemented in the form of a software functional unitand is sold or used as an independent product, it may be stored in acomputer readable storage medium. Based on such understanding, essenceof the technical solutions of the present disclosure, or a part of thetechnical solution contributing to the prior art, or a part of thetechnical solutions, may be implemented in the form of a softwareproduct. The computer software product is stored in a storage medium,and includes a plurality of instructions for enabling a computer device(may be a personnel computer, a server, or a network device or the like)or a processor to execute all or a part of the steps of the methods inthe embodiments of the present disclosure. The foregoing storage mediumincludes a variety of media capable of storing program codes, such as aUSB disk, a mobile hard disk, a read-only memory (ROM), a random accessmemory (RAM), a magnetic disk, an optical disk or the like.

The foregoing descriptions are merely specific embodiments of thepresent disclosure, rather than limiting the protection scope of thepresent disclosure. Any skilled one familiar with this art could readilythink of variations or substitutions within the disclosed technicalscope of the present disclosure, and these variations or substitutionsshall fall into the protection scope of the present disclosure.Accordingly, the protection scope of the claims should prevail over theprotection scope of the present disclosure.

The invention claimed is:
 1. A method for signal compensation,comprising: receiving, by a receiver via N receiving antennas, aplurality of channel estimation preamble signals sent by M transmittingantennas of a remote transmitter, wherein the plurality of channelestimation preamble signals contain measurement signals of the Mtransmitting antennas of the remote transmitter, wherein every twoadjacent measurement signals of one of the plurality of channelestimation preamble signals are isolated by at least one voidsubcarrier, and wherein a same number of void subcarriers are includedbetween every two adjacent measurement signals; determining, by thereceiver, channel estimation parameters from the M transmitting antennasto the N receiving antennas according to the plurality of channelestimation preamble signals, wherein M and N are integers larger than 1,wherein the plurality of channel estimation preamble signals comprisefirst pilot signals of the M transmitting antennas; receiving, by thereceiver, data signals and second pilot signals sent on a first datasymbol by the M transmitting antennas; determining, by the receiver,channel phase shift parameters from the M transmitting antennas to the Nreceiving antennas; and determining, by the receiver, signalcompensation for the data signals arrived at the N receiving antennasthat are sent on the first data symbol by the M transmitting antennasaccording to the channel estimation parameters and the channel phaseshift parameters, wherein the determining the signal compensation isperformed using the following formula: $\begin{bmatrix}{\hat{x}}_{1}^{k} \\\vdots \\{\hat{x}}_{M}^{k}\end{bmatrix} = {{\left\lbrack {\left\lbrack H_{\xi}^{d} \right\rbrack^{\dagger}H_{\xi}^{d}} \right\rbrack^{- 1}\left\lbrack H_{\xi}^{d} \right\rbrack}^{\dagger}\begin{bmatrix}{y_{1}^{k}(l)} \\\vdots \\{y_{N}^{k}(l)}\end{bmatrix}}$ wherein {circumflex over (x)}_(m) ^(k) represents a datasignal transmitted on the k^(th) subcarrier of the l^(th) data symbol bythe m^(th) transmitting antenna in the M transmitting antennas, y_(n)^(k)(l) represents a signal arrived at the n^(th) receiving antenna ofthe receiver s from a data signal transmitted on the k^(th) subcarrierof the I^(th) data symbol by the M transmitting antennas, ∀m={1, . . .,M}, ∀n={1, . . . ,N}, [

_(ξ) ^(k)]^(†) represents a conjugate matrix of

_(ξ) ^(k), $H_{\xi}^{k} = {\quad{\begin{bmatrix}{{\hat{H}}_{11}^{k}e^{j\;\xi_{11}}} & \ldots & {{\hat{H}}_{1\; M}^{k}e^{j\;\xi_{1\; M}}} \\\vdots & \vdots & \vdots \\{{\hat{H}}_{N\; 1}^{k}e^{j\;\xi_{N\; 1}}} & \ldots & {{\hat{H}}_{N\; M}^{k}e^{j\;\xi_{N\; M}}}\end{bmatrix},}}$

_(nm) ^(k) in

_(ξ) ^(k) represents a channel estimation parameter on the k^(th)subcarrier between the m^(th) transmitting antenna of the remotetransmitter and the n^(th) receiving antenna of the receiver,

_(nm) ^(k)=y_(n) ^(k)(t)/s^(k), ∀n={1, . . . ,N}, k∈K, K represents asubcarrier set of the m^(th) transmitting antenna of the remotetransmitter for transmitting the channel estimation preamble signal,s^(k) represents a pilot signal of the k^(th) subcarrier in theplurality of channel estimation preamble signals, y_(n) ^(k)(t)represents a pilot signal arrived at the n^(th) receiving antenna of thereceiver s from a pilot signal on the k^(th) subcarrier in the t^(th)channel estimation preamble signal of the remote transmitter,$\quad\begin{bmatrix}e^{j\;\xi_{11}} & \ldots & e^{j\;\xi_{1\; M}} \\\vdots & \vdots & \vdots \\e^{j\;\xi_{N\; 1}} & \ldots & e^{j\;\xi_{N\; M}}\end{bmatrix}\mspace{40mu}$ represents channel phase shift parametersfor signals arrived at the N receiving antennas that are sent on theI^(th) data symbol by the M transmitting antennas, and is expressed bythe following formula: $\quad{\begin{bmatrix}e^{j\;\xi_{11}} & \ldots & e^{j\;\xi_{1\; M}} \\\vdots & \vdots & \vdots \\e^{j\;\xi_{N\; 1}} & \ldots & e^{j\;\xi_{NM}}\end{bmatrix} = {{\left\lbrack {\begin{bmatrix}{\overset{\sim}{H}}^{p_{1}} \\\vdots \\{\overset{\sim}{H}}^{p_{|p|}}\end{bmatrix}^{\dagger}\begin{bmatrix}{\overset{\sim}{H}}^{p_{1}} \\\vdots \\{\overset{\sim}{H}}^{p_{|p|}}\end{bmatrix}} \right\rbrack^{- 1}\begin{bmatrix}{\overset{\sim}{H}}^{p_{1}} \\\vdots \\{\overset{\sim}{H}}^{p_{|p|}}\end{bmatrix}}^{\dagger}\begin{bmatrix}{y_{1}^{p_{1}}(l)} \\\vdots \\{y_{N}^{p_{1}}(l)} \\{y_{1}^{p_{2}}(l)} \\\vdots \\{y_{N}^{p_{p}}(l)}\end{bmatrix}}}$ wherein y_(n) ^(p)(l) represents a pilot signal arrivedat the N receiving antennas s from a pilot signal transmitted on a pilotsubcarrier p of the l^(th) data symbol by the M transmitting antennas, prepresents any pilot subcarrier in a pilot subcarrier set {p₁, . . .p_(|p|)} of the l^(th) data symbol, and

^(p) is expressed by the following formula:${\overset{\sim}{H}}^{p} = {\begin{bmatrix}{{\hat{H}}_{11}^{p}s_{1}^{p}} & \ldots & {{\hat{H}}_{1\; M}^{p}s_{M}^{p}} & 0 & \ldots & 0 & 0 & \ldots & 0 \\0 & \ldots & 0 & {{\hat{H}}_{21}^{p}s_{1}^{p}} & \ldots & {{\hat{H}}_{2\; M}^{p}s_{M}^{p}} & \vdots & \ldots & \vdots \\\vdots & \ldots & \vdots & \vdots & \vdots & \vdots & 0 & \ldots & 0 \\0 & \ldots & 0 & 0 & \ldots & 0 & {{\hat{H}}_{N\; 1}^{p}s_{1}^{p}} & \ldots & {{\hat{H}}_{NM}^{p}s_{M}^{p}}\end{bmatrix}.}$
 2. A receiver, comprising: N receiving antennas,configured to receive a plurality of channel estimation preamble signalssent by M transmitting antennas of a remote transmitter, wherein theplurality of channel estimation preamble signals contain measurementsignals of the M transmitting antennas of the remote transmitter,wherein every two adjacent measurement signals of one of the pluralityof channel estimation preamble signals are isolated by at least one voidsubcarrier, and wherein a same number of void subcarriers are includedbetween every two adjacent measurement signals; and a determining unit,configured to determine channel estimation parameters from the Mtransmitting antennas to the N receiving antennas according to theplurality of channel estimation preamble signals, M and N are integerslarger than 1, wherein the plurality of channel estimation preamblesignals comprise first pilot signals of the M transmitting antennas;wherein the N receiving antennas are further configured to receive datasignals and second pilot signals sent on a first data symbol by the Mtransmitting antennas; and wherein the determining unit is furtherconfigured to determine channel phase shift parameters from the Mtransmitting antennas to the N receiving antennas, and determine signalcompensation for the data signals arrived at the N receiving antennasthat are sent on the first data symbol by the M transmitting antennasaccording to the channel estimation parameters and the channel phaseshift parameters, wherein the determining unit determines the signalcompensation using the following formula: $\begin{bmatrix}{\hat{x}}_{1}^{k} \\\vdots \\{\hat{x}}_{M}^{k}\end{bmatrix} = {{\left\lbrack {\left\lbrack H_{\xi}^{k} \right\rbrack^{\dagger}H_{\xi}^{k}} \right\rbrack^{- 1}\left\lbrack H_{\xi}^{k} \right\rbrack}^{\dagger}\begin{bmatrix}{y_{1}^{k}(l)} \\\vdots \\{y_{N}^{k}(l)}\end{bmatrix}}$ wherein {circumflex over (x)}_(m) ^(k) represents a datasignal transmitted on the k^(th) subcarrier of the l^(th) data symbol bythe m^(th) transmitting antenna in the M transmitting antennas, y_(n)^(k)(l) represents a signal arrived at the n^(th) receiving antenna ofthe receiver s from a data signal transmitted on the k^(th) subcarrierof the I^(th) data symbol by the M transmitting antennas, ∀m={1, . . .,M}, ∀n={1, . . . ,N}, [

_(ξ) ^(k)]^(†) represents a conjugate matrix of

_(ξ) ^(k), ${H_{\xi}^{k} = \begin{bmatrix}{{\hat{H}}_{11}^{k}e^{j\;\xi_{11}}} & \cdots & {{\hat{H}}_{1M}^{k}e^{j\;\xi_{1M}}} \\\vdots & \vdots & \vdots \\{{\hat{H}}_{N\; 1}^{k}e^{j\;\xi_{N\; 1}}} & \cdots & {{\hat{H}}_{NM}^{k}e^{j\;\xi_{NM}}}\end{bmatrix}},$

_(nm) ^(k) in

_(ξ) ^(k) represent a channel estimation parameter on the k^(th)subcarrier between the m^(th) transmitting antenna of the remotetransmitter and the n^(th) receiving antenna of the receiver,

_(nm) ^(k)=y_(n) ^(k)(t)/s^(k), ∀n={1, . . . ,N}, k∈K, K represents asubcarrier set of the m^(th) transmitting antenna of the remotetransmitter for transmitting the channel estimation preamble signal,s^(k) represents a pilot signal of the k^(th) subcarrier in theplurality of channel estimation preamble signals, y_(n) ^(k)(t)represents a pilot signal arrived at the n^(th) receiving antenna of thereceiver s from a pilot signal on the k^(th) subcarrier in the t^(th)channel estimation preamble signal of the remote transmitter,$\begin{bmatrix}e^{j\;\xi_{11}} & \cdots & e^{j\;\xi_{1M}} \\\vdots & \vdots & \vdots \\e^{j\;\xi_{N\; 1}} & \cdots & e^{j\;\xi_{NM}}\end{bmatrix}\quad$ represents channel phase shift parameters forsignals arrived at the N receiving antennas that are sent on the I^(th)data symbol by the M transmitting antennas, and is expressed by thefollowing formula: $\begin{bmatrix}e^{j\;\xi_{11}} & \cdots & e^{j\;\xi_{1M}} \\\vdots & \vdots & \vdots \\e^{j\;\xi_{N\; 1}} & \cdots & e^{j\;\xi_{NM}}\end{bmatrix}{\quad{= {{\left\lbrack {\begin{bmatrix}{\overset{\sim}{H}}^{p_{1}} \\\vdots \\{\overset{\sim}{H}}^{p_{p}}\end{bmatrix}^{\dagger}\begin{bmatrix}{\overset{\sim}{H}}^{p_{1}} \\\vdots \\{\overset{\sim}{H}}^{p_{p}}\end{bmatrix}} \right\rbrack^{- 1}\begin{bmatrix}{\overset{\sim}{H}}^{p_{1}} \\\vdots \\{\overset{\sim}{H}}^{p_{p}}\end{bmatrix}}^{\dagger}\begin{bmatrix}{y_{1}^{p_{1}}(l)} \\\vdots \\{y_{N}^{p_{1}}(l)} \\{y_{1}^{p_{2}}(l)} \\\vdots \\{y_{N}^{p_{p}}(l)}\end{bmatrix}}}}$ wherein y_(n) ^(p)(l) represents a pilot signalarrived at the N receiving antennas s from a pilot signal transmitted ona pilot subcarrier p of the l^(th) data symbol by the M transmittingantennas, p represents any pilot subcarrier in a pilot subcarrier set{p₁, . . . p_(|p|)} of the l^(th) data symbol, and

^(p) is expressed by the following formula:${\overset{\sim}{H}}^{p} = {\begin{bmatrix}{{\hat{H}}_{11}^{p}s_{1}^{p}} & \cdots & {{\hat{H}}_{1M}^{p}s_{M}^{p}} & 0 & \cdots & 0 & 0 & \cdots & 0 \\0 & \cdots & 0 & {{\hat{H}}_{21}^{p}s_{1}^{p}} & \cdots & {{\hat{H}}_{2M}^{p}s_{M}^{p}} & \vdots & \cdots & \vdots \\\vdots & \cdots & \vdots & \vdots & \vdots & \vdots & 0 & \cdots & 0 \\0 & \cdots & 0 & 0 & \cdots & 0 & {{\hat{H}}_{N1}^{p}s_{1}^{p}} & \cdots & {{\hat{H}}_{NM}^{p}s_{M}^{p}}\end{bmatrix}.}$